literature review on road design

Subsurface Drainage Practices in Pavement Design, Construction, and Maintenance (2022)

Chapter: chapter 2 - literature review.

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6 Early literature on road building offers some clues about when and how people became aware that excessive moisture in pavement structures is detrimental to pavement performance. MacAdam (1820), for example, is often mentioned (e.g., Moulton 1980) as having observed that, regard- less of the thickness of the structure, many roads in Great Britain deteriorated rapidly when the subgrade was saturated. However, instead of thinking that road building on a large scale began with the Roman Empire and that people only started observing the adverse effects of excessive moisture for pavements many centuries later, it may be more realistic to think of roads as being, from their very inception, engineering solutions to the problem of wet, weak, unimproved soils impeding the movement of people, goods, and armies. As Ksaibati and Kolkman (2006) observed, “They are called ‘high ways’ because early road builders knew it was necessary to construct roads above the ground and away from water.” Roman roads, which were substantial stone structures built to resist flooding and environmental damage and to move the armies and goods needed to sustain the empire, were considered to be the most advanced roads ever built until the 19th century, and some of them remained usable for more than 1,000 years. Post–Roman Empire road construction arguably originated in France in the mid-1700s, where Trésaguet oversaw the construction of multilayered gravel road surfaces on crowned subgrades with side ditches for drainage, first in Paris and later as standard practice throughout France (Lay 1992). However, to keep roadway surfaces at roughly the same height as the surrounding countryside, Trésaguet’s road design was typically built in a trench, which created drainage problems. These were addressed by design modifications that included digging deeper side ditches, making the surface layer as solid as possible, and constructing the road surface with a cross slope to hasten rainfall runoff. In the early 1800s, Telford applied Trésaguet’s road design approach to road building in Wales and developed it further, using a mixture of gravel and larger paving stones that became known as “Telford pitching.” To prevent pooling of water and erosion of the road surface, Telford raised the pavement structure above the ground level wherever possible, and where it was not, Telford drained the area around the roadside (Lay 1992). At around the same time, Metcalf emerged as a strong advocate of well-drained road structures in England (Lay 1992). Early modern road engineers such as Trésaguet, Telford, Metcalf, and MacAdam (1820) called attention to the need for stronger, more durable road surfaces that were less susceptible to the damaging effects of excess moisture in the road structure and foundation. MacAdam advo- cated less substantial gravel layer thicknesses in roads but more durable materials—specifically, carefully placed (MacAdam 1824) and carefully sized moisture- and frost-resistant crushed stone (Lay 1992). He favored the use of an adequate but not excessive cross slope, elevation of the road structure above the water table, and runoff into side ditches. C H A P T E R   2 Literature Review

Literature Review 7   The Industrial Revolution of the late 18th and early 19th centuries, which began in Great Britain, brought, among its many technological innovations, powerful new ways of moving people and goods, including the steam locomotive and gasoline-powered automobiles and trucks. The Industrial Revolution also brought about unprecedented population growth and an explosive growth in trade, both of which resulted in enormously increased volumes of traffic on roads. At the time of the Industrial Revolution, France was known for the quality of its roads, in no small part because of Trésaguet’s efforts mentioned earlier, but roads in other countries throughout Europe, including Great Britain, were in poor condition and were not fit to meet the challenges of the new era (Hunter 1985; Grübler 1990). Depending on local soil and rainfall conditions, roads that were sufficient to support animal-drawn carts bearing people and goods were often not sufficient to support the much heavier loadings of motorized vehicles and much higher traffic volumes of rapidly growing economies. As Ridgeway (1982) explained in NCHRP Synthesis 96: Pavement Subsurface Drainage Sys- tems, the soil–aggregate mixtures used as surfaces for roads built by the methods recommended by Trésaguet, Telford, Metcalf, and MacAdam were densely graded and compacted mixtures, intended to protect weaker layers below from both loads and water infiltration. As bituminous materials and Portland cement came into use as binders for road surfaces, these densely graded soil–aggregate mixtures became base materials, a use for which their low permeability may not have been a desirable characteristic. Despite the typically poor drainability of asphalt- and concrete-surfaced roads built in the United States during the first half of the 20th century, their performance was “satisfactory under the traffic and load conditions that existed before the Inter- state era” (Ridgeway 1982). However, concern about the role of excess water in exacerbating visible pavement distress and accelerating pavement failure increased as the weight and volume of traffic on roads increased. Cedergren et al. (1972) illustrated the main sources of water in pavement structures, as shown in Figure 1. Moulton (1980) grouped types of drainable subsurface water into two categories: • Groundwater, which is defined as water existing in the natural ground in the zone of satura- tion below the water table; and • Precipitation infiltration, which seeps into the pavement through joints and cracks in the pavement surface, through the pavement surface itself to whatever degree it is permeable, and from ditches along the side of the road. Moulton (1980) thus distinguished between subsurface drainage systems for ground- water control and subsurface drainage systems for infiltration control. Cedergren et  al. (1973) illustrated the main points of infiltration of water into pavement structures, as shown in Figure 2. “Pavement subsurface drainage systems,” as they are commonly understood in the context of pavement design rather than hydrological design, are intended primarily to address infiltration of water through joints and cracks and in some situations shallow groundwater movements, including lateral groundwater seepage, fluctuations in groundwater levels, and capillary action. Such systems typically consist of the following components: • A permeable base, either stabilized or unstabilized, that is either daylighted to a side ditch foreslope or drained by longitudinal edge drains; • A separator layer, of either untreated granular material or geosynthetic material, with a gradation (in the case of a granular separator) or design opening size (in the case of a geo- textile) selected to prevent fines from an underlying embankment fill or subgrade layer from infiltrating into the permeable base layer above and reducing its permeability;

8 Subsurface Drainage Practices in Pavement Design, Construction, and Maintenance Source: Adapted from Cedergren et al. 1972. Notes: AC = asphalt concrete; PCC = Portland cement concrete. Figure 1. Sources of water in pavements. Source: Adapted from Cedergren et al. 1973. Figure 2. Points of inltration of water into AC and PCC pavements.

Literature Review 9   • Longitudinal edge drains, if present (i.e., if the permeable base layer is not daylighted to a side ditch), placed in backfilled trenches along the pavement edge on one or both sides, depending on the geometry of the pavement cross section; • Outlet pipes that drain the longitudinal edge drains to the ditches; and • Headwalls to protect the ends of the outlet pipes. According to Moulton (1980, 15), although free (drainable) water from melting ice lenses may exist above the water table, it is generally considered to be groundwater because “the water that feeds the growth of ice lenses originates at the base of the capillary fringe (i.e., at the water table), and no frost action can take place without water from this source.” Meltwater is sometimes treated as a component of the drainable water that is quantified as the design inflow in the design of pavement subsurface drainage systems. Excess subsurface moisture may cause or exacerbate the following problems: • Slope instability (which may lead to sliding of cut slopes above roadways and collapse of fill slopes below roadways); • Visible pavement distress (including rutting, cracking, and potholes in asphalt pavements; faulting, cracking, and corner breaks in jointed concrete pavements; punchouts in continuously reinforced concrete pavements; and pumping, blowholes, and settlement along lane–shoulder joints in all types of pavements); and • Diminished pavement strength, stability, and durability (including stripping of asphalt binder from aggregates in asphalt-bound layers, erosion of slab support under concrete pavements, D-cracking of concrete containing aggregates susceptible to freeze–thaw damage, expansive cracking of concrete containing reactive aggregates, and weakening of unbound base and foundation layers). The use of open-graded, and thus more permeable, granular base layers began to emerge as a way to improve pavement drainability in the 1940s. The term “drainage blanket” was often used to describe a very permeable base layer that had a length (in the direction of flow) and width that were large relative to its thickness. A rational approach to the estimation of the time required to drain a “pervious subbase,” based on the base permeability, slope, and amount of drainable water in the pavement struc- ture, was proposed by Izzard (1944). This approach assumes that water reaches the subbase through joints and cracks in the pavement and along the edge of the pavement. On flat grades, the capacity of the base to carry water longitudinally was assumed to control drainage, unless a continuous longitudinal underdrain was located at the pavement edge. Otherwise, drainage was assumed to be controlled by the capacity of outlets spaced along the shoulder. The maximum outlet spacing decreases as the grade of the roadway decreases. To improve pavement drainage, Izzard (1944) recommended that, on flat grades, either continuous longitudinal underdrains should be provided or the subbase should be extended across the shoulder (daylighted). Glossop (1947) examined the effects of soil types, soil profiles, and sources and movements of water in pavement structures on the bearing capacity, settlement, and frost heave suscep- tibility of road foundations. He also offered recommendations for the use of different types of drains (open ditches, French drains, horizontal drains, and interceptor drains) to maintain slope stability and adequate pavement drainage. Casagrande and Shannon (1952) observed that base courses beneath airport pavements at several air bases in the northern United States became saturated under some conditions, and they identified frost action and infiltration through the surface as the main sources of water responsible for base saturation. They developed a “time-to-drain” approach to permeable base design and compared the results obtained with the results of laboratory model tests and

10 Subsurface Drainage Practices in Pavement Design, Construction, and Maintenance full-scale field tests. The comparisons showed that the proposed formulas were satisfactory for use in the design of base drainage. Casagrande and Shannon (1952) also presented sets of equations—and a dimensionless chart in the form of a set of curves for solving the equations—for determining how long it takes for a base that becomes fully saturated by water inflow during a rainfall event to drain to a lower level of saturation by outflow from the base to ditches alongside the roadway, either through longitudinal edge drains and outlets, if present, or by seepage through the base to the ditch slope, if the base is daylighted. Similar time-to-drain equations and charts were developed by Barber and Sawyer (1952), Cedergren (1974), Moulton (1980), and Markow (1982). Casagrande and Shannon (1952) noted that as the slope of the pavement became flatter or the thickness of the base became greater, the predictions obtained from their time-to-drain equations differed more widely from observed values. Liu et al. (1983) re-examined the time- to-drain approach and concluded that the underlying assumptions of a linear phreatic surface (water level) in the base and an impermeable subgrade below the base were not as realistic as assumptions of a parabolic phreatic surface and some degree of permeability of the sub- grade. Liu et al. (1983) developed new time-to-drain equations based on these more realistic assumptions and showed that the results obtained were generally in good agreement with the field data obtained by Casagrande and Shannon (1952) in full-scale tests. The second approach to permeable base design is the “depth-of-flow” approach described by Moulton (1980). This approach is based on the idea that the thickness of the base should be greater than or equal to the depth of water flow when the base is saturated, and that the steady flow capacity of the base should be greater than or equal to the rate of inflow. The required base thickness is determined from equations or a chart as a function of the rate of inflow, drainage length, slope, and base permeability. The approach taken to determine the required permeable base thickness (i.e., the time-to- drain approach or the depth-of-flow approach) dictates which set of equations is subsequently used to determine the design flow capacity for longitudinal edge drains of a specific type and diameter. This is done by setting the pipe capacity equal to the discharge from a unit length of pavement multiplied by the spacing between outlets (Babu et al. 2019). Moulton (1980) summarized in great detail the literature and practice on characterizing key inputs to pavement subsurface drainage design—namely, the geometry of the flow domain (the geometric design of the highway and prevailing subsurface conditions), the subgrade and pave- ment layer material properties (particularly their permeability, effective porosity, and frost susceptibility), and the characteristics of the climate (precipitation and temperature), that dictate how much water could infiltrate the pavement structure and how frost action might influence water movement in the pavement and foundation. Moulton (1980) also discussed how pavement subsurface drainage construction influenced the sequence of pavement con- struction operations and discussed economic considerations related to the use of subsurface drainage systems. Rainfall intensity–duration–frequency relations are commonly used to characterize precipi- tation for flood forecasting and drainage design. The U.S. Weather Bureau (Herschfield 1961) developed maps of rainfall intensity as a function of frequency and duration for any location within the 48 contiguous U.S. states. The U.S. National Oceanic and Atmospheric Administra- tion’s National Weather Service operates a website, the Precipitation Frequency Data Server, that can be used to obtain precipitation frequency estimates for any location in the 50 U.S. states, the District of Columbia, and the U.S. territories. The two main approaches to estimating the rate at which water infiltrates a pavement struc- ture are the infiltration ratio approach (Cedergren et al. 1972, Cedergren et al. 1973, Cedergren

Literature Review 11   1974) and the crack inltration approach (Ridgeway 1976). In Cedergren’s approach, the 1-hr- duration/1-yr-frequency inltration rate is multiplied by a coecient with a value less than 1 depending on the pavement surface type. Ridgeway, however, suggested that rainfall inltration depended more on duration than on intensity and was directly related to the degree of cracking. Procedures for identifying (a) existing moisture-accelerated distress and (b) conditions favorable to the development of moisture-accelerated distress were developed by Carpenter et al. (1979, 1981a, 1981b). e potential for excessive moisture in a pavement structure at any given location in the 48 contiguous U.S. states was characterized using ornthwaite’s climate classi- cation system (ornthwaite 1948). Carpenter et al. (1979, 1981a, 1981b) combined temperature and moisture measures, including ornthwaite’s moisture index (TMI), with soil deformation characteristics to produce a map of nine climatic zones of the United States (Figure 3), wherein the Roman numerals I, II, and III denote wet, seasonally wet, and dry subgrade conditions, respectively, and the letters A, B, and C denote freeze, freeze–thaw, and non-freeze winter soil conditions, respectively. is type of characterization can be useful in identifying areas where pavements may be more vulnerable to moisture-related damage because of subgrade moisture levels at or approaching saturation, either seasonally or throughout the year, as well as subgrade weakening due to thaw, either in the spring or repeatedly throughout the winter. A simplied version of this map, which divides the United States into four climatic zones (wet- freeze, wet-nonfreeze, dry-freeze, and dry-nonfreeze), was adopted for use in characterizing pavement test sites for the Strategic Highway Research Program’s (SHRP) Long-Term Pavement Performance (LTPP) studies and is shown in Figure 4. NCHRP Synthesis 96 (Ridgeway 1982) summarized the basic principles and then–state of the practice of subsurface pavement drainage system design, construction, and maintenance, including topics such as the assessment of the need for drainage, the sources of water in pave- ments, the ways in which water moves in pavements, subsurface drainage design inputs and criteria, the subsurface drainage design process, and the retrotting of longitudinal edge drains as part of existing pavement maintenance or rehabilitation. e synthesis attributed the increased attention toward pavement subsurface drainage in the 1970s and 1980s to both increased awareness of the adverse eects of excessive moisture on pavement performance (e.g., Carpenter et al. 1979) I-A I-B I-C II-A II-B II-C III-A III-B III-C Source: Adapted from Carpenter et al. 1979. Base map created at Mapchart.net. Figure 3. Nine climatic zones of the United States based on moisture and temperature.

12 Subsurface Drainage Practices in Pavement Design, Construction, and Maintenance and the emergence of new types of edge drains and lter materials, as reected by the develop- ment of prefabricated underdrains (e.g., Healy and Long 1971) and criteria for the use of lter fabrics (Bell and Hicks 1980). Among the main conclusions of NCHRP Synthesis 96 (Ridgeway 1982) were that Darcy’s law is suitable for use in the design of subsurface drainage systems; that the primary source of drainable water in pavement structures is inltration; that water held in the pavement structure by capillary forces cannot be removed by subsurface drainage systems; that the permeability requirements for lateral ow in permeable bases are high because of the low hydraulic gradients and small areas of ow that are characteristic of permeable base layers; and that appropriately designed lters (granular materials of suitable gradation or lter fabrics of suitable apparent opening size) are essential to prevent permeable base materials, trench backll materials, and longitudinal edge drains from becoming clogged. NCHRP Synthesis 96 (Ridgeway 1982) summarized information on pavements constructed with subsurface drainage systems in California, Kentucky, Michigan, New Jersey, and Pennsylvania. e treated and untreated permeable bases in these pavements were judged to be not overly dicult to construct, cost-competitive with dense-graded base layers, and performing satisfac- torily. e synthesis reported more mixed results for retrotted edge drains, citing examples from California, Georgia, and Iowa. One of the problems mentioned was that the quality of support at the pavement edge can be diminished during the process of retrotting edge drains. Another problem was that retrotted edge drains are not likely to be able to remove much water from an existing base layer that is densely graded. Dempsey et al. (1982) observed that base permeabilities of at least 25 /day are necessary for longitudinal edge drains to have some inuence on base moisture content. Cedergren et al. (1973) recommended the installation of edge drains in test sections to assess their eectiveness before making a decision to retrot edge drains in large pave- ment rehabilitation projects. Ring and Mottola (1984) referred to the ingress of moisture into pavement structures as the greatest contributor to accelerated deterioration. They discussed the range of adverse Wet-Freeze (WF) Wet-Nonfreeze (WNF) Dry-Freeze (DF) Wet-Nonfreeze (WNF) Dry-Nonfreeze (DNF) Source: Adapted from SHRP 1990a, b. Base map created at Mapchart.net. Figure 4. Four climatic zones of the United States as dened for LTPP studies.

Literature Review 13   effects that moisture can have on asphalt, concrete, granular base, and subgrade layers; described case studies of drainable systems constructed as experimental pavements; and offered rec- ommendations for the design of aggregate mixtures to achieve a balance between stability and drainability. In 1992, the FHWA published the results of a study titled Drainable Pavement Systems, commonly referred to as Demonstration Project 87, or more briefly as Demo 87, to provide guidance for the design of subsurface drainage systems to remove infiltrated water from pavement structures. A computer program titled Drainage Requirements in Pavements (DRIP 1.0) was developed as a companion to the participants’ notebook for a Demo 87 training course. In 1998, a National Highway Institute course, Pavement Subsurface Drainage Design (No. 131026), was developed to train state DOT personnel in the use of DRIP 1.0 for the design, construction, and maintenance of subsurface drainage systems according to the practices recommended in Demo 87. An updated version of the DRIP software (2.0) and user guide were released in 2002 (Mallela et al. 2002), and the corresponding National Highway Institute training course was updated in 2008. Hassan et al. (1996) reviewed field studies (Espinoza 1993; Zubair et al. 1993) on pavement subsurface drainage in Indiana and reported that the findings had led to several changes in subsurface drainage system practices in Indiana, including cessation of the use of geocomposite drains, recommendations for improvements to subdrain outlet protection and marking, imple- mentation of a program for routine inspection and maintenance, and requirements for contrac- tors to inspect edge drain installations and be responsible for any repairs needed. NCHRP Synthesis 239: Pavement Subsurface Drainage Systems (Christopher and McGuffey 1997) presented an update to NCHRP Synthesis 96 (Ridgeway 1982) on the state of the practice of pavement subsurface drainage system use, while describing NCHRP Synthesis 96 as a still- useful reference for the concepts and details of subsurface drainage system design. NCHRP Synthesis 239 examined design issues such as the type and quality of aggregate to be used in permeable bases, compaction requirements for open-graded aggregates, requirements for asphalt and cement binders, and the use of geosynthetics. It also summarized available information on the effects of design, construction, and maintenance decisions on the performance of pave- ment subsurface drainage systems. Much of the drainage system design information provided in NCHRP Synthesis 239 was obtained from the training materials for FHWA’s Demo 87 project. Design details and state standards and specifications were reviewed for both subdrainage systems in new pavement construction and subdrain retrofitting for existing pavements. The synthesis identified various difficulties that can arise with the use of permeable base layers, edge drains, and outlets, as well as ways in which those difficulties can be overcome, including proper material selection (e.g., permeable base gradation, quality, and durability, and the content of asphalt or cement binder, if used), traffic control during construction, video inspection and flow testing prior to accep- tance, and training of construction and inspection personnel. Several DOTs reported that unstabilized, highly permeable base layers are difficult to construct and are unable to support construction traffic, and therefore the DOTs adopted gradation changes and the use of asphalt or cement binders to improve base stability at the expense of some degree of base permeability. As in FHWA’s Demo 87 training course, NCHRP Synthesis 239 strongly emphasizes the need for appropriately designed, constructed, and maintained subsurface drainage systems to achieve acceptable long-term pavement performance. The synthesis cites several studies (e.g., Cedergren 1974; Forsyth et al. 1987; Ray and Christory 1989; Christory 1990; Smith et al. 1994; Hagen and Cochran 1996), as well as the results of the synthesis’ survey of state DOTs, in support of the conclusion that “although there may be a real or perceived lack of cost–benefit data on the use

14 Subsurface Drainage Practices in Pavement Design, Construction, and Maintenance of subsurface drainage, the preponderance of data show a direct relationship between improved performance and extended pavement life.” NCHRP Synthesis 239 does, however, acknowledge that the degree to which subsurface drainage systems may benefit pavement performance and be cost-effective also depends on whether their use is warranted, given decision factors that include climate conditions, subgrade per- meability, and traffic levels. Cited research suggests that pavement subsurface drainage systems may not be beneficial at locations with subgrade permeabilities of more than about 10 ft/day (Grogan 1992) or with rainfall of less than about 16 in./yr (Wells and Nokes 1993). The synthe- sis suggests developing decision matrices to guide agencies in determining when subsurface drainage systems are warranted, based on factors such as the following: • Functional classification; • Design life; • Pavement and shoulder type and width; • Hydraulic considerations, including infiltration and time to drain; • Longitudinal and transverse grades; • Climate, including rainfall, temperature, and frost action; • Subgrade characteristics, including permeability; • Contribution of drainage layer to pavement structural capacity; • Constructability of drainage system components; • Maintenance requirements, capabilities, and commitment; and • Initial and life-cycle costs. NCHRP Synthesis 285: Maintenance of Highway Edgedrains (Christopher 2000) was con- ducted as an extension of NCHRP Synthesis 239 (Christopher and McGuffey 1997). According to NCHRP Synthesis 285, most of the state DOTs that responded to the NCHRP Synthesis 239 survey agreed that maintenance was the most important factor contributing to the long-term performance of pavement subsurface drainage systems. Nonetheless, many respondents (most of whom were designers) had little information on drainage system maintenance activities conducted by their departments or the effects of such maintenance. NCHRP Synthesis 285 was therefore conducted to identify (a) design and construction details and procedures that facili- tate edge drain maintenance and reduce the amount of maintenance required and (b) practices for effective maintenance of edge drain system components. A subsurface drainage system’s effectiveness in removing water from a pavement structure and in contributing to good long-term pavement performance can be enhanced, as NCHRP Syn- thesis 285 points out, by taking future maintenance needs and techniques into consideration in the design and construction phases. Among the design details and construction procedures that were identified as contributing to drainage system effectiveness, performance, and ease of future maintenance were the following: • Slotted longitudinal pipes in open-graded aggregate backfill in geotextile-lined trenches, all sized appropriately (pipe slot size, backfill gradation, and geotextile apparent opening size) to prevent migration of aggregate and fines into pipes; • Pipe, connection, and outlet dimension and configuration details (pipe diameter, pipe slope, connection radius, outlet spacing, and outlet height above the design flow level of the ditch) to facilitate water flow, video inspection, and pipe flushing; • Large cast-in-place or precast headwalls sloped flush with the ditch slope to facilitate mowing; • Careful pipe trench backfill compaction control to avoid both pipe crushing and future densi- fication of edge drain trench backfill; and • Permanent (painted or stamped) pavement markings to indicate outlet locations, as opposed to vertical delineator posts that are likely to be damaged by mowing equipment.

Literature Review 15   Video inspection prior to acceptance was identified as the only effective means of detecting construction-related problems with edge drains, such as crushing of pipes. Among the recom- mended post-acceptance inspection and maintenance practices were the following: • Regularly scheduled visual inspection of outlets and headwalls; • Periodic video inspection of longitudinal pipes and outlets; • Observation of water flow from outlets after storm events or during flow testing (e.g., pouring water on the pavement surface using a water truck); • Checking that rodent screens, if present, are not blocked; • Checking that the headwalls and outlet openings are not obscured by vegetation, blocked by sedimentation, damaged, or settled; and • Regularly scheduled pipe flushing using high-pressure water jets. Communication between design, construction, and maintenance groups within state DOTs was emphasized as an important part of coordinating the design, construction, and mainte- nance of subsurface drainage systems that will perform as expected in removing excess water from pavement structures. Training construction and inspection personnel was identified as an important step to ensuring proper edge drain functioning because, according to the synthesis, most edge drain system failures can be traced to poor construction and inadequate inspection. NCHRP Synthesis 285 also examined the costs of edge drain maintenance, strategies to reduce maintenance costs, and ways to increase edge drain maintenance effectiveness. A commitment to edge drain maintenance was concluded to be crucial for edge drains to perform as expected and contribute to good long-term pavement performance. The costs of edge drain maintenance efforts were judged to be far outweighed by the benefits of effective pavement drainage in terms of increased pavement life and performance. Conversely, according to the synthesis, edge drains that are installed but not adequately maintained may result in additional costs associated with poorer pavement performance (e.g., shorter life to first rehabilitation and increased repair needs). However, the synthesis acknowledged the limited availability of quantitative informa- tion to substantiate the cost savings achievable by installing and maintaining edge drains versus installing edge drains but not maintaining them. This was identified as a subject warranting future research. Daleiden (1998) conducted 287 video inspections of highway edge drain systems in 29 states and found that only one-third of the inspected edge drain systems were performing as intended. One-third of the inspected systems had non-functional outlets, and the other third had longi- tudinal edge drainpipes that were either non-functional or could not be inspected because of physical obstructions. While subsurface pavement drainage systems (e.g., a permeable base layer and edge drains) were increasingly used by many U.S. states by the mid-1990s, controversy persisted over the design and benefits of subsurface drainage (Harrigan 2002). NCHRP conducted a series of studies between 1995 and 2007 to address the following two key questions concerning sub- surface pavement drainage: (1) Do the various design features of subsurface drainage systems contribute to improved performance of asphalt concrete (AC) and Portland cement concrete (PCC) pavements? (2) Are the features cost-effective, and if so, under what conditions? Obser- vations and critical analyses of the performance of in-service pavements with and without subsurface drainage, in all of the major climatic zones of the United States, were judged to be the only way that credible evidence could be gathered concerning the true effects of subsurface drainage on performance (Harrigan 2002). The first of these studies, NCHRP Project 1-34 (Yu et al. 1998), was conducted using data obtained from surveys of 91 AC pavement sections at 22 sites in 10 U.S. states and one Cana- dian province, and 46 PCC pavement sections at 16 sites in seven U.S. states and one Canadian

16 Subsurface Drainage Practices in Pavement Design, Construction, and Maintenance province, as well as additional data on about 300 AC and PCC pavement sections in the FHWA’s Rigid Pavement Performance and Rehabilitation database and the SHRP’s LTPP database. However, pavement sections from the LTPP Specific Pavement Studies (SPS) AC pavement (SPS-1) and PCC pavement (SPS-2) experiments, the only LTPP experiments developed to permit comparison of drained and undrained pavement sections at the same sites, were not included because they were not of sufficient age at the time the project was underway. The key findings of NCHRP Project 1-34, summarized in NCHRP Research Results Digest 268 (Harrigan 2002), encompassed a variety of observations of differences in distress and roughness for AC and PCC pavement sections with and without edge drains and with different base types (including unbound dense-graded, asphalt- or cement-treated dense-graded, unbound permeable, and asphalt- or cement-treated permeable), as well as daylighted bases of various types. The findings were judged to be limited, however, by the small number of sites and their lack of distribution throughout the United States, the fact that most of the drained (permeable base) pavement sections were relatively young and had carried relatively little traffic, and the lack of information about whether and how well the subsurface drainage systems in the drained pavement sections were functioning (Harrigan 2002). Three follow-up studies were commissioned by the NCHRP Project 1-34 panel. NCHRP Project 1-34B (Hall et al. 2000) critically reviewed the results of NCHRP Project 1-34 and developed an experimental plan to evaluate and test NCHRP Project 1-34’s key findings, using data from the LTPP SPS-1 and SPS-2 experiments, under NCHRP Project 1-34C (Hall and Correa 2003). Field testing of the functionality of the subsurface drainage features in the LTPP SPS-1 and SPS-2 field sections and further analyses of the relationship between subsurface drainage, features, and pavement performance (using distress, roughness, and deflection data from the SPS-1 and SPS-2 sites) were conducted under NCHRP Project 1-34D (Hall and Crovetti 2007). Possible reasons for the lack of consensus on the cost-effectiveness and benefits of sub- surface pavement drainage systems for pavement performance were summarized by Hall and Crovetti (2007, p. 1) as follows: The reasons often mentioned for why subsurface pavement drainage systems do not always yield improve- ments in performance include inadequate design, improper construction, and inadequate maintenance. If, however, these were the only reasons, then they could be countered by—and improvements in pavement performance and pavement life could be consistently achieved by—adequate design, proper construction, and adequate maintenance. Yet there are at least two other reasons why drained pavements do not con- sistently perform better than undrained pavements. First, subsurface drainage systems are sometimes used in locations where they are not needed (e.g., places with low amounts of rainfall or with subgrade soils that have sufficient natural drainage characteristics so that water rarely, if ever, collects in the constructed pavement layers long enough to contribute to any damage). Second, subsurface drainage systems are sometimes used in pavements where they are not needed, such as pavements with other design features (such as thickness or dowels) that make them unlikely to develop the types of damage that would be exacerbated by excess water. NCHRP Project 1-34D was conducted using distress, roughness, and deflection data retrieved from Release 19 (January 2005) of the LTPP database for all SPS-1 and SPS-2 sites, along with the results of drainage outlet inspections and subdrainage system flow time tests conducted at all of the sites to assess the functioning of the subsurface drainage systems. The flow meter used in the flow time testing is shown in Figure 5. The same flow meter and other equipment used to conduct the flow time testing are shown in Figure 6. The AC and PCC pavements in the SPS-1 and SPS-2 experiments were located in 18 and 14 states, respectively (SPS-1 AC sites in AL, AZ, AR, DE, FL, IA, KS, LA, MI, MT, NE, NV, NM, OH, OK, TX, VA, and WI; SPS-2 PCC sites in AZ, AR, CA, CO, DE, IA, KS, MI, NV, NC, ND, OH, WA, and WI), in both cases distributed across all of the four main climatic zones of the United States and across a wide range of annual average rainfall amounts and hydrological soil

Literature Review 17   Source: Hall and Crove 2007. ll Figure 5. Flow meter used in ow testing at LTPP SPS-1 and SPS-2 sites. Figure 6. Water truck and equipment used in ow testing at LTPP SPS-1 and SPS-2 sites. types (from high to very low inltration rates). e SPS-1 sites were predominantly located on more lightly tracked routes than the SPS-2 sites, with more than half of the SPS-2 sites having carried more truck trac than all but two of the SPS-1 sites. e results of the testing and analyses conducted under NCHRP Project 1-34D did not identify any aspect of the behavior or performance of the AC and PCC pavement structures in the SPS-1 and SPS-2 experiments that was improved by the presence of subsurface pavement drainage. Instead, the measures of pavement behavior and performance analyzed for these

18 Subsurface Drainage Practices in Pavement Design, Construction, and Maintenance pavements—namely, deflection response, roughness, rutting, faulting, and cracking—were found to be influenced by the stiffness, not the drainability, of the base layers. Overall, the best- performing AC pavements in the SPS-1 experiment were those with the stiffest bases (dense- graded asphalt-treated base layers), whether drained or undrained. The best-performing PCC pavements in the SPS-2 experiments were those with bases that were neither too weak (untreated aggregate) nor too stiff (lean concrete). These included both the sections with drained permeable asphalt-treated bases and the sections with undrained hot-mix asphalt (HMA) bases and cement-aggregate-mixture bases. NCHRP Project 1-34D recommended that the need for subsurface pavement drainage should be assessed using the TMI and precipita- tion data to identify sites with year-round or seasonal excesses of available moisture, as well as using county soil reports and soil taxonomy information to identify subgrade soils with poor natural drainage characteristics. Bhattacharya et al. (2009) reported on an evaluation of the performance of 24 projects in 15 counties in California where concrete pavements were constructed with subsurface edge drains. California has constructed subsurface drainage systems according to a wide range of designs, but many of them were later found to have become ineffective because of deficien- cies in design, materials, construction, and maintenance. Of the 24 projects surveyed, fewer than 30 percent had functioning edge drains. These projects were typically in areas of higher rainfall. At most of the remaining sites, little or no maintenance had been done, and the drainpipes were clogged with soil. Bhattacharya et al. (2009) concluded that subsurface drainage systems installed as part of new construction, with larger diameter drainpipes, deep trenches, and treated permeable bases, contributed to better pavement performance than that of shallow edge drains with slotted pipes retrofitted to existing pavements. On the basis of the study results, Bhattacharya et al. (2009) recommended that the use of subsurface drainage systems should be based on an assessment of the rainfall characteristics of the site, the permeability of the natural soil, and whether there is a long-term commitment to maintenance of the edge drain system. They also suggested that the use of edge drains should be considered only in isolated locations of poor drainage and not necessarily throughout the entire length of a project. They noted that video inspection was facilitated by the use of larger- diameter (4-in.) drainpipes and that maintenance was facilitated by the use of dual-outlet systems (i.e., where edge drains and outlets form sequential open loops along the roadway, with the end of each loop and the beginning of the next one forming a pair of adjacent drainage outlets). Bhattacharya et al. (2009) observed that the use of edge drain systems did not yield an evident improvement in long-term concrete pavement performance beyond those already offered by load transfer devices (dowel bars and tie bars), daylighted permeable bases, and AC interlayers. An NCHRP IDEA study (Stormont et al. 2009) yielded an innovative method for draining water from a pavement base layer and preventing water from reaching the subgrade by using a geocomposite capillary barrier drain (GCBD). A GCBD consists of three layers: a transport layer (a specially designed geotextile) beneath the base, a capillary barrier (geonet) beneath the transport layer, and a separator (geotextile) beneath the geonet and above the subgrade. Water that infiltrates into the pavement and enters the base is prevented from moving into the under- lying subgrade by the capillary barrier formed by the geonet. The transport layer (a special geotextile) becomes increasingly hydraulically conductive as it gets wet. Water drains along the slope of the transport layer, and if the transport layer does not become saturated, no water will break through into the capillary barrier. The bottom separator protects the geonet from becoming contaminated with subgrade soil. A GCBD also cuts off capillary rise of water in the underlying soil, and if the overlying base and transport layer become saturated owing to an extraordinary infiltration event, it provides saturated drainage in the geonet. Ceylan et al. (2013) conducted field investigations of the effects of drainage outlet conditions on 56 jointed plain concrete pavements and eight AC pavements in Iowa. They found that (a) while

Literature Review 19   less than 20 percent of the edge drain outlets of the concrete pavements surveyed were damaged, approximately 65 percent were blocked to some degree; and (b) while less than 10 percent of the edge drains of the asphalt pavements surveyed were damaged, approximately 45 percent were blocked to some degree. In the case of concrete pavements built with granular bases consisting of recycled concrete, blockage occurred in some subdrain outlets due to the for- mation of precipitated calcium carbonate, known as tuff or tufa. Concrete pavement bases constructed with a blend of recycled concrete aggregate and virgin aggregate were found to exhibit fewer outlet blockages due to tufa formation than bases constructed entirely with recycled concrete aggregate. In their field investigations, Ceylan et al. (2013) saw little evidence of outlet blockages due to rodents but did see evidence of blockages due to rodent screens, so they advised against the use of rodent screens. Ceylan et al. (2013) observed that, although greater degrees of blockage reduce the flow rate of water in outlet pipes, they did not necessarily stop the flowing water from exiting the drainage system through the outlet pipes unless the outlet was completely blocked. They also found that little pavement distress was observed near blocked subsurface drainage outlet spots, although shoulder distresses (shoulder drop off and cracking) were observed more often near blocked drainage outlets than near clear outlets. Both the field observations and the limited perfor- mance analysis from this study led Ceylan et al. (2013) to conclude that drainage outlet condi- tions did not have a significant effect on pavement performance in Iowa. Summary Centuries of road building experience, going as far back as the Roman Empire, have shown that excess moisture in pavement structures and foundations can adversely affect pavement behavior and performance. Early modern road building practices recognized the importance of protecting road structures from excess moisture, and the growth in road traffic weights and volumes brought about by the Industrial Revolution intensified the need for roads that were resistant to moisture-related damage. Among the problems that excess moisture can cause or exacerbate are slope instability, visible pavement distress of various types, and diminished pave- ment strength, stability, and durability. In the United States, roads built during the first half of the 20th century were typically poorly drained but performed satisfactorily under the traffic and load conditions of the time. Con- cepts and procedures for the design of subsurface pavement drainage systems were developed in the 1940s and improved through the 1990s, including implementations using nomographs and computer software. Such systems are intended primarily to address infiltration of water through joints and cracks, and in some situations, shallow groundwater movements (including lateral groundwater seepage, fluctuations in groundwater levels, and capillary action). The state of the practice of subsurface drainage system use, design, construction, and maintenance has been summarized in three prior NCHRP syntheses published between 1982 and 2000. This current synthesis was conducted to provide a more current assessment of state DOT practices and experiences with regard to subsurface pavement drainage systems.

Subsurface drainage is known to pavement professionals to be an important factor affecting pavement performance and preservation of public investment, and numerous studies have emphasized its importance.

The TRB National Cooperative Highway Research Program's NCHRP Synthesis 579: Subsurface Drainage Practices in Pavement Design, Construction, and Maintenance documents the current state of practice by departments of transportation (DOTs) for subsurface drainage, which is not always considered as a critical component when it comes to design, construction, and maintenance of pavement.

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State of the Art in Road Design Standards: A PIARC Literature Review

This literature review is the first of two planned publications of PIARC Task Force 4.1 “Road Design Standards” in the period 2020 – 2022. PIARC considered importance of comparison international road design standards to check their updated status and the degree of their readiness to face the forthcoming innovations in the road mobility. The report presents a literature review in the field of road design standards based on reviewing reports, guidelines, and research papers on the subject matter. It is the first document since many years comparing road design standards in several countries. The document aims to identify similarities and differences between the approaches adopted in different countries and evaluates the possible need of their adaptation to the requirements of a rapidly changing world in the field of road transport systems: new technologies, changes in mobility modes (new propulsion techniques, new personal transport mode, and connected and autonomous driving) and availability of multiple diffused data sources (Big Data). The comparison and conclusions were drafted basing on the answers received to the Questionnaire launched among the members of Task Force 4.1. Ultimately, the comparison covered 15 countries from around the world: Austria, Australia, Belgium (Wallonia), Canada (Quebec), Chile, China, Czechia, France, Germany, Italy, Japan, Mexico, Poland, Portugal and Spain. The literature review focuses on reviewing the following topics: road classification, speed in road design standards, traffic composition and multimodal consideration in road design standards, design criteria, driving performance and human factors, design parameters considered in road infrastructure design.

• Record URL: https://www.piarc.org/en/order-library/38657-en-State%20of%20the%20Art%20in%20Road%20Design%20Standards?directory=%7B%7D
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• Abstract reprinted with permission of the World Road Association – PIARC.

World Road Association (PIARC). Task Force on Road Design Standards (4.1)

• Publication Date: 2022
• Media Type: Digital/other
• Features: Appendices; Figures; Glossary; References; Tables;
• Pagination: 126p

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• TRT Terms: Design standards ; Highway design ; Literature reviews ; Questionnaires
• Subject Areas: Design; Highways;

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Dealing with uncertainties in the design phase of road projects

International Journal of Managing Projects in Business

ISSN : 1753-8378

Article publication date: 23 December 2022

Issue publication date: 18 December 2023

Uncertainty management (UM) in projects has been a point of attention for researchers for many years. Research on UM has mainly been aimed at uncertainty analyses in the front-end and managing uncertainty in the construction phase. In contrast, UM components in the design phase have received less attention. This research aims to improve knowledge about the key components of UM in the design phase of large road projects.

Design/methodology/approach

This study adopted a literature review and case study. The literature review was used to identify relevant criteria for UM. These criteria helped to design the interview guide. Multiple case study research was conducted, and data were collected through document study and interviews with project stakeholders in two road projects. Each case's owners, contractors and consultants were interviewed individually.

The data analysis obtained helpful information on the involved parties, process and exploit tools and techniques during the design phase. Johansen's (2015) framework [(a) human and organisation, (b) process and (c) tools and techniques)] was completed and developed by identifying relevant criteria (such as risk averse or risk-taker, culture and documentation level) for each component. These criteria help to measure UM performance. The authors found that owners and contractors are major formal UM actors, not consultants. Empirical data showed the effectiveness of Web-based tools in UM.

Research limitations/implications

The studied cases were Norwegian, and this study focussed on uncertainties in the project's design phase. Relevant criteria did not cover all the criteria for evaluating the performance of UM. Qualitative evaluation of criteria allows further quantitative analysis in the future.

Practical implications

This paper gave project owners and managers a better understanding of relevant criteria for measuring UM in the owners and managers' projects. The paper provides policy-makers with a deeper understanding of creating rigorous project criteria for UM during the design phase. This paper also provides a guideline for UM in road projects.

Originality/value

This research gives a holistic evaluation of UM by noticing relevant criteria and criteria's interconnection in the design phase.

• Large projects
• Uncertainty management
• Design process
• Human and organisation
• Tools and techniques

Shabani, R. , Malvik, T.O. , Johansen, A. and Torp, O. (2023), "Dealing with uncertainties in the design phase of road projects", International Journal of Managing Projects in Business , Vol. 16 No. 8, pp. 27-57. https://doi.org/10.1108/IJMPB-02-2022-0050

Emerald Publishing Limited

Copyright © 2022, Rouzbeh Shabani, Tobias Onshuus Malvik, Agnar Johansen and Olav Torp

Published by Emerald Publishing Limited. This article is published under the Creative Commons Attribution (CC BY 4.0) licence. Anyone may reproduce, distribute, translate and create derivative works of this article (for both commercial and non-commercial purposes), subject to full attribution to the original publication and authors. The full terms of this licence may be seen at http://creativecommons.org/licences/by/4.0/legalcode

1. Introduction

Projects are efforts to create unique products and values that benefit society ( Johansen, 2015 ). Managing projects is not an easy endeavour. Constraints, challenges and risks exist in the different project phases. Opportunities exist to reduce project costs and time and improve projects' performance simultaneously through introducing scope reductions, planning choices and so on ( Kendrick, 2015 ). Projects' dynamic environment results in many changes and variations, and stakeholders with different needs exemplify such dynamicity.

Various models describe construction project phases and stages ( Johansen et al ., 2019 ). According to Project Management Institute (PMI), all projects generally go through initiation, planning, execution and closing ( PMBOK, 2013 ). Johansen et al . (2019) suggested that different industries have various phase models. Models used in public road construction projects in the Nordic countries are akin to Morris' (2002) and the PRINCE2 model ( Hedeman and Seegers, 2009 ). Figure 1 shows Johansen et al . (2019) 's typical project phases. The pre-study phase entails concept definition, feasibility studies and project appraisal. In the design phase, the owners define the project's core plan and a detailed design that consultants or contractors run. In the execution phase, the contractor will conduct the construction design, and the final stage will be producing the final product and commissioning the project.

Most models focus on project development (planning) and execution (building the road or railroad) and less on the front-end (project appraisal) and operation stage, where the actual project value is delivered ( Johansen, 2015 ). Our adjusted model focusses mainly on the design phase, and this paper will focus on uncertainty related to detailed design and design for construction.

Uncertainty relates to different parameters, such as cost, time, quality and scope, and needs to be addressed to avoid failures ( Andenæs et al. , 2020 ). The design phase is one of the most uncertain and complex ( Ackermann et al. , 2014 ). The concept is not chosen, the design and development of the concept are in the early phase and the project delivery model is not yet decided ( Johansen et al. , 2019 ). The iterative process of developing the solution is combined with more formal efforts like planning the construction phase and developing the contract strategy. Designers, owners and contractors interact with each other to satisfy all parties' needs. Otherwise, the project may face unsatisfied users and owners, failure in cost, time, design and environmental problems ( Klakegg and Haavaldsen, 2011 ).

Atkinson et al. (2006) said projects' premature definition led to cost and time overrun and emphasised the design phase's necessity. Recognising design phase uncertainties helps estimate their impact on the execution phase and addresses problems sooner ( Vaagen et al. , 2017 ; Rostami and Oduoza, 2017 ). For example, one of the problems could be the changes in design and probable discussions amongst designers, owners and contractors. Although measures to deal with changes might be defined in contracts, their management and belonging details and parties' satisfaction are essential and involves considerable uncertainty. The ability to predict future scenarios and related uncertainties could help project parties be ready to deal with future issues, prepare resources and conduct necessary activities ( Farooq et al. , 2018 ). Besides, understanding the uncertainty of different design options would help make better design decisions.

Changes after the design phase often cost more for owners ( Samset, 2010 ). Design changes can increase projects' costs by 2–21% ( Aslam et al. , 2019 ), and they need to be noticed early. Early uncertainty evaluation satisfies not only the iron triangle of cost, time and quality, but also creates value for different project parties in the operation phase (project delivery). Construction projects create value through design management ( Savolainen et al. , 2018 ). Late recognition of design uncertainties and poor response might lead to poor performance and low value.

With all necessities for the design phase, research is lacking on the uncertainty of projects and evaluation of important components in the process of uncertainty management (UM) simultaneously ( Osipova, 2007 ; Wuni et al. , 2021 ). Such evaluation of the design phase evaluates UM broadly by considering important criteria in each component and noticing their interconnection. There exist some models and tools which focus on UM.

Arena et al. (2013) developed a tool providing managers with a dynamic representation of adopted risk response strategies and supporting their decision-making by analysing risk profiles. These tools can also analyse the company's risk management (RM) system and identify its strengths and weaknesses. Adam and Lindahl (2019) developed a company dynamic response map (CDRM) risk management model using dynamic capabilities and evaluated Arena et al .’ (2013) model to better respond to risk and opportunities according to dynamic capabilities. Wang et al. (2016) developed an infrastructure risk assessment framework based on the Analytical Hierarchy Process (AHP)-based risk assessment and considered the environmental, project implementation and decision-making behaviour risks. Dikmen et al. (2022) developed a tool and process model to estimate project risk and contingency level by evaluating complexity factors and contextual information such as contract situation, managerial and technical risk cost and mitigation strategies. There exist other tools such as Monte-Carlo simulation-based approach by Han et al. (2017) or the systematic approach to managing uncertainties using the multiple-case approach by Augusto et al. , (2019) .

Johansen (2015) developed a framework for managing project uncertainties with reliance on the three components Human and organisation , Process and Tools and techniques . This framework supported practical UM, which was applied in different industries and projects ( Hald et al. , 2008 ; Johansen et al. , 2014 ; Johansen, 2015 ). This framework's advantages are as follows: First, these components are not removable from the UM study. If one component is removed, the UM in the project is considered incomplete, but it will still be able to deal with some uncertainty aspects. Second, the framework is broad, meaning it could cover many criteria within it, but the criteria are not originally designed for analysing UM in the design phase. Humans and organisations had more generic criteria such as roles and responsibilities, competency and effective communication. Third, the framework suggested that the three components should be integrated and interrelated to each other and work at a similar performance level. For instance, assume if there are competent people without suitable tools for handling uncertainties or vice versa. The model's simplicity and holistic nature make it useful for analysis of UM in large project – but it needs to be developed further with specific criteria for the design phase.

How is uncertainty managed in the design phase?

What are the relevant criteria of UM in the design phase of road projects?

This paper has the following structure. After the introduction explains the topic's importance, section two provides the theory about uncertainty and its management in the project's design phase. Section three presents the research method. Section four explains the results, and section five elaborates on the discussion. The final section presents the paper's conclusion and possibilities for further research.

2. Theory about uncertainty management in the design phase

The theory sections consist of three parts. (1) The first part covers the design phase, its characteristics and related challenges. (2) The second part defines UM and the relation between risk and uncertainty in construction projects. (3) The last part introduces the criteria for UM.

2.1 The design phase of construction projects

Design is a process; usually, most designs are not done before execution begins, and there is often an overlap between design and execution ( Smith et al. , 2006 ). The design process balances clients' needs and actual understanding of project execution. Misalignment always exists between the risk and profits of designers and clients. On the one hand, designers want to benefit from the design; on the other hand, clients want the best design. Therefore, designers should balance between profit and the best design for the satisfaction of both parties ( Lohne et al. , 2017 ).

Design management includes determining consultants' duties, resolving project content, planning, resourcing and determining deliverables and controlling and interfering when project objectives are not met ( Chapman, 2001 ). Design process characterise with iteration, using simple ideas for testing solutions, having sequences as design phases, sequences for information exchange and the influence of external agencies and client changes ( Chapman, 2001 ; Johansen et al. , 2019 ). This process is seen as communication between problem and solution aided by the three activities of analysis, synthesis and evaluation ( Lawson, 2006 ). The road design process could have the following steps: feasibility study and preliminary design and detailed design based on the study by Rwakarehe and Mfinanga (2014) . Design is not a logical and tidy process in projects and is semi-messy ( Lawson, 2006 ) and wicked problems with no single solution but multiple solutions ( Buchanan, 1992 ).

Different demands and requirements in the project's design convey many challenges for involved parties. Lohne et al . (2017) represented the ethical concerns practitioners meet in the design phase of architecture, engineering and construction (AEC) projects. The most important challenges mentioned were hidden agendas and power actions from different parties. Therefore, the parties need to acknowledge that various requirements and interdependencies in the design phase need to be handled. The design phase is an ongoing and continuous process ( Lawson, 2006 ). It could have uncertainties related to lack of constructors' cooperation ( Samset, 2010 ), setting more ambitious projects goals, ill-defined project scope and weak design ( Johansen et al. , 2019 ), inappropriate design, poor engineering, delayed in design activities, delay in buying land and change in raw material cost ( Smith et al. , 2006 ; Mhatre et al. , 2017 ) as well as lack of designers' involvement in the primary decision process together with the owner, which might lead to organisational risk ( Jaafari, 2001 ).

Projects with high technical, procurement and contract complexity require careful design. Besides, political, economic and environmental issues also influence them ( Johansen, 2015 ). In other research by Asadi et al. (2018) , they found that shortages in design documents could affect safety performance and construction projects negatively. Thus, design consequence develops in later project phases, and design difficulties rely on project complexity and the project type, which could be different. Early management of design uncertainties may mitigate these effects.

2.2 Uncertainty management

Galbraith (1974) said that uncertainty stems from a lack of information. He explains that uncertainty undermines firms' ability to plan proactively and make proper decisions before project execution. Risk and uncertainty are used interchangeably in which risks are related to something negative, and uncertainty is a negative or positive event that has been identified but is unknown ( Ward and Chapman, 2003 ; Walker et al ., 2017 ). Many authors declared the relationship between uncertainty and risk in the literature on uncertainty and RM ( Jaafari, 2001 ; Johansen et al. , 2019 ).

Risk is part of uncertainty with negative consequences on the project's objective. It will be an opportunity with positive effects ( Wideman, 1992 ). According to Thamhain (2013) , many managers spend much time on risk-related issues in the projects' early and design phases. Perminova et al. , (2008) said that uncertainty “is an event or a situation which was not expected to happen, regardless of its prediction”. Uncertainty is when established facts are questioned and thereby the basis for calculating risk (known negative event) or opportunities (known positive events).

Known knowns : According to identified risk source, a probability can be assigned to the occurrence of the risk event;

Known unknowns : The risk source has been identified, but the probability of a risk event occurring cannot be determined;

Unknown knowns : Risk source and associated probabilities are known but kept confidential and

Unknown unknowns : No risk source and risk event have been identified.

The range of growing uncertainty from “known knowns” to “unknown unknowns” distinguishes risk from uncertainty and unexpected events, which connects the concept to the availability of information and decision-making.

Chapman and Ward (2007) defined five preliminary questions in addressing uncertainties: “Who are involving parties?”, “What are the motives of the parties?”, “How is it to be done?”, “What resources are required?” and “When should it be done?” These are main questions for tackling uncertainties in each project's phase.

Each phase may call for different ways to address uncertainties. For example, price increases of construction materials for building a bridge in the initial phase cause owners to consider higher contingency or contractors change their suppliers to find low prices suppliers and compensate the cost or look for cheaper solutions. This uncertainty in the execution phase might need different strategies such as cost-cutting tasks, reducing unnecessary work and changes in design.

2.3 Criteria for uncertainty management

Figure 2 depicts the Johansen's (2015) theoretical framework utilised in this paper, with “human and organisation”, “processes” and “tools and techniques” as the three main UM components. All three need to be functional and work together if “living uncertainty management” should be obtained in the project's design phase.

Klakegg et al . (2010) suggested that for conducting uncertainty analysis, both the sophisticated criteria associated with “good” and the practical options associated with “simple” are needed. He noted a tendency towards more complex tools and techniques; this might be due to larger and more complex projects over the years. Zidane et al. (2013) identified project characteristics that serve to differentiate between small, medium, large and megaprojects. These include the budget, the timeline, the number of stakeholders and the complexity level. These characteristics might help decide the complexity level in processes, tools and techniques and organisations. This section describes criteria with three components of human and organisation, process and tools and techniques.

2.3.1 Criteria in human and organisation component

The “human and organisation” component embraces people's professions, abilities and roles in project teams. This part begins with a human's explanation, continues with roles and concludes with the organisation. UM is primarily done by humans who have intuition, knowledge and experience. Humans are both important and challenging components of UM ( Hillson and Murray-Webster, 2017 ).

Generally, people could have different opinions about the same issues seen in projects and related to project risk. Smith et al. (2006) linked risk to personal opinions and explained that RM behaviour could be divided into the roles of being a risk-taker or risk averse. Project owners and investors are risk-takers, and contractors are risk averse ( Smith et al. , 2006 ). Contractors could take many risks if they get paid. Van Os et al. (2015) showed that the relation between group members is weakened by the responsibility of the risk shifted to other stakeholders. Shi et al. (2015) found that the management of social risks should focus on “sufficient communication”, “timely response”, “effective trust building” and “enhancement of social benefit”. Chapman (1999) said that efficient management of design projects requires clear and effective communication. Risk analysis and management in these projects must be communicated and understood clearly.

A competent and skilled workforce can act effectively against uncertainty. Besides personal skills, stakeholders' cooperation is necessary for UM ( Chapman and Ward, 2011 ; Walker et al ., 2017 ). According to Klakegg et al . (2010) , project owners' lack of involvement hinders uncertainty analyses and management. Karlsen (2011) emphasised the role and commitment of the senior managers in UM process for being effective. Adafin et al. , (2021) identified the consultants' competency as a budgetary risk factor in projects' performance in the design phase. According to Podgórska and Pichlak (2019) , change in key personnel during the design phase hinders the project's progress. Rashid and Boussabiane (2021) found that project manager's trait and cognitive biases influence their risk-taking behaviour with the project outcome. We concluded that a lack of participation, poor communication, cognitive biases and incompetence may be the leading causes of poor UM performance.

Risk responsibility/ownership ( Klakegg et al ., 2010 ; Johansen, 2015 );

Workforce competency ( Chapman and Ward, 2011 ; Adafin et al. , 2021 );

Team members' role ( Osipova, 2008 ; Chapman and Ward, 2011 ; Johansen et al. , 2019 );

Effective communication ( Osipova, 2008 ; Aslam et al. , 2019 ) and

Organisational culture ( Karlsen, 2011 ; Rashid and Boussabiane, 2021 ).

2.3.2 Criteria in the process component

This section starts with process definition, UM process and, finally, criteria which improve UM process. A process involves a beginning, ending and expected results. Chapman and Ward offer Shape, Harness and Manage Project Uncertainty (SHAMPU), a nine-step paradigm for addressing project uncertainties. There are other processes in the Project Risk Analysis and Management (PRAM) and Project Management Body of Knowledge (PMBOK) guide ( Austeng et al. , 2005a ). Scandinavian countries mostly use a step-by-step process for uncertainty and risk analysis based on successive principles ( Lichtenberg, 2000 ; Klakegg, 1994 ). In PMBOK, the RM process includes planning, identification, analysis, responses, monitoring and control of the risks.

Projects with a long timeframe need regular risk assessment processes and updates. The RM process focusses on the needs and requirements of clients and the different tools and techniques that can be used ( Smith et al. , 2006 ). Johansen et al. (2019) defined the general steps for UM based on the literature study from previous research on UM and RM in the project as follows: (1) defining the goals for UM (initiation), (2) identifying key stakeholders, (3) identifying uncertainties and determining its effect on project objective (quantifying), (4) prioritising opportunities and threats, (5) checking if the response has expected effect (review) and (6) updating of uncertainty register and searching for new opportunities and plan and execution of new responses (follow). According to Johansen et al. (2016) and based on empirical data from complex public and private projects, there is often poor performance in managing opportunities in projects.

Lichtenstein (1996) stated that different factors determine the best RM method and process. His study found seven important factors in the risk assessment model: usability, credibility, complexity, completeness, adaptability, validity and cost. Qazi and Simsekler (2021) developed a simulation-based risk assessment model to help an organisation prioritise risks and assign resources correspondingly to the critical risks identified. Prioritising and assigning resources could be one of the essential criteria related to the process.

Whilst Simister (2004) and Johansen (2015) emphasised the importance of undertaking RM as a formal process aligned with the overall project management approach, Krane and Langlo (2010) underline the necessity of informal interaction and communication. They claim that informal actions make it possible to cooperate and respond quickly without spending unnecessary resources. However, a formal structure must exist as a “backbone” for the informal interaction to work. Formal and informal meetings facilitate communication amongst different actors.

Equal consideration for risk and opportunity ( Johansen et al. , 2016 );

Usability ( Lichtenstein, 1996 );

Formal or informal ( Simister, 2004 ; Krane and Langlo, 2010 ; Johansen, 2015 );

Documentation ( Johansen et al. , 2019 ) and

Collaboration and information exchange level ( Osipova, 2008 ).

2.3.3 Criteria in the tools and techniques component

In this section first tools and techniques were defined, then some tools were introduced and finally concluded with some identified factors. “Tools and techniques” are analytical and visualisation methods and techniques for project uncertainty identification, analysis and management. Klakegg et al . (2010) showed that criteria for analytical processes like UM processes could differ from good to simple. Each one (good and simple) has its own advantages and disadvantages. For example, good (complex) could be precise, objective and so on. Simple could be understandable by anyone in the project.

Tools can be an advanced Excel spreadsheet, estimation tool for cost uncertainty (Anslag 4.0), web-based risk registers which is called Process Information Management System (PIMS) web and uncertainty matrices. Techniques are brainstorming, interviews, checklists and the Delphi method. Choosing the right project, deciding upon the best design and estimating the time and cost of the project are all done to minimise the risk involved. Still, it is not part of the UM. Project owners utilise different tools and techniques to identify, estimate and manage the uncertainty that is not shared with other partners (design firms or contractors) ( Johansen, 2015 ).

Different methods and tools combine the power of computer-based tools with structured processes and systematic approaches for uncertainty, risk analysis and management ( Klakegg et al. , 2010 ). Qazi et al. (2020) said that interdependency modelling of uncertainty had been discussed using different qualitative and quantitative techniques. These models were based on the interpretive ranking process and system dynamics ( Mhatre et al. , 2017 ), Artifitial Intelligence (AI) ( Afzal et al. , 2021 ), fuzzy system ( Valipour et al. , 2015 ), meta-network analysis ( Wang et al. , 2021 ), Building Information Modelling (BIM) ( Zhou et al. , 2021 ) and multi-criteria decision-making model ( Albogamy and Dawood, 2015 ; Burcar Dunovic et al. , 2016 ). All these models were used to forecast the influence of uncertainties on project objectives.

Complex or simple ( Klakegg et al. , 2010 );

Precise or imprecise ( Klakegg et al. , 2010 );

Resource demanding or less resource demanding ( Klakegg et al ., 2010 );

Visualisation capability ( Smith et al. , 2006 ; Johansen, 2015 ) and

Documentation capability ( Johansen, 2015 ).

3. Research method

This study aimed to improve the knowledge about the key components of design phase UM. The literature review helped to know UM and UM in the project's design phase as well as the relative criteria for the UM's components which was introduced by Johansen (2015) . Second, it was essential to understand how UM was done in the project design phase, which was accomplished by case studies. The case study employed document study and interviews to develop new knowledge regarding the application of the UM in the design phase ( Gustafsson, 2017 ). Interview as a qualitative strategy demonstrated how uncertainties are managed in projects. Project manager interviews supplemented document study data.

3.1 Literature review

As shown in Table 1 , a systematic literature review started with selecting important keywords for study topics. We investigated human and organisation, processes and related tools and techniques of UM. To decide the different literature's relevance for this paper, one of the authors searched all journal articles in all issues (2015–2022). The search concentrated on databases Scopus, Web of science and Emerald as illustrated in Table 1 . In the first step, articles were filtered based on search keys in title-abstract-keyword, journal articles, English articles and peer-reviewed articles. In the second step, abstracts of the papers were read, and articles were chosen based on the inclusion criteria with a focus on three components of UM and RM models in construction, infrastructure and highway projects. The numbers in the last column of Table 1 show the total number of articles after reading the abstract. Then in the third step, abstract and conclusion of the articles were read and data were reflected on paper.

The number in the parentheses indicates the articles that can be accessed by reading the abstract. The inclusion criteria in the third step were if the result was relevant to uncertainty framework, models and components of UM or RM in projects. All articles (45) were read and reflected upon in the introduction, theory section and discussion.

3.2 Choice of research method

Yin (2018) suggests using case studies and histories to answer how and why questions and explanatory research studies. Multiple case studies allow the evaluation of a phenomenon in different situations. Case studies help understand case complexity, such as changes over time, the work processes and the interaction of different parties. A case study also facilitates grabbing the project's contextual condition ( Yin, 2018 ). RQs in this study seek to know how uncertainties are managed in the design phase, identify key criteria for UM framework and how relevant framework components play a role in UM. The research is a case study as a qualitative approach which uses empirical data, a document study and interviews to answer the RQs. The process of UM was not examined in detail in the design phase of Norwegian projects, and we required some criteria for determining its performance. A case study involving two cases with two different owners was the most appropriate way to understand the complexity of cases. This helps to compare cases and evaluate them with identified criteria.

Researchers can see differences and similarities between the two cases, and the data are more reliable ( Baxter and Jack, 2015 ). Two cases were homogeneous in the context of the project's operation. This study analyses and verifies theoretical propositions using theory and data. Triangulation is a research strategy using different data sources ( Bryman, 2016 ), and we used this strategy for data collection to improve the findings' reliability. Table 2 illustrates the characteristics of two road projects used for data collection. We conducted semi-structured interviews as part of the data collection.

Construction of a cable bridge and surrounding infrastructure.

Construction of a four-lane highway.

The old road was a corridor and part of the national transport network with many problems related to safety and traffic with a high risk of accidents which needs to be improved. The estimated cost of the project is around US$621m. The new four-lane road will replace the previous two-lane road. Higher speed limits and a shorter length, together with higher quality, will reduce travel time and increase safety on the highway. This project has four double tunnels and the road length is approximately 19 km.

3.3 Document study

A document study was performed to get information about project characteristics, important uncertainties related to the two case studies and project uncertainty analysis processes. Document study was a preliminary study before doing the interviews. There are some sources of risk documentation in non-traditional ways: interactive websites, digital media, video reports, workshops, chat rooms, wikis, discussion groups and electronic files.

In the process of document study, experienced authors, at the first step, choose the related documents. Then each author reviewed the documents and wrote the project's description and related information from meetings during the project's design phase. All these documents are publicly available and do not contain confidential information. During the research process, information was completed with new documents in contact with project parties. The studied documents are presented in Table 3 :

3.4 Semi-structured interviews

Semi-structured interviews can be conducted by developing an interview guide covering specific topics. The interviewer is not obliged to follow the interview guide; sometimes, the interviewer could ask some questions that do not exist in the interview guide to get a better insight into the topic ( Bryman, 2016 ).

After the pre-interview, note-taking and recording are utilised to collect data. The cases differed; experts interviewed client project managers, winning contractors and designers. Interviews lasted one to one-and-a-half hours, depending on the interviewees' schedules. We used coding based on essential criteria for each UM component for data analysis. For instance, we chose documentation-level, formal or informal, information exchange for the process component. Table 4 shows the paper's interview process and provides information regarding interview duration, interviewees' role in projects, data collection method and follow-up meetings or contacts with interviewees.

We interviewed about the UM process, tools and methods and related criteria. We asked about people involved in the UM process during the project's design phase and how they acted in such a process. Seven interviews have been conducted for two projects.

The findings from the study are presented according to Johansen's framework components in the theory section (2–3), including human and organisation, processes and tools and techniques. Findings also cover the identified criteria for each component. The summary of findings from three components can be found in Appendix .

4.1 The human and organisation component in the design phase

Case 1 document examination indicated that various stakeholders, health, environment and safety (HES), geotechnical consultants and owner design managers participated in UM. The owner's UM process is built on group work led by a competent facilitator (competent: based on experience and education) who has taught people to manage it. All members of UM team conduct risk registers throughout various periods.

We chose a highly qualified contractor based on price, experience, and design competition. Besides, the people in our team have enough experience in UM process. Senior managers support choosing competent people in our team and the contractor. Organization have some guidelines and procedures for choosing qualified contractors.

Different roles were involved in the UM’s meeting with competency in their tasks. Their competency was based on the years of experience and the successful project they conducted

We have previously carried out major infrastructure projects in the city and have a group of people with local affiliation who want to help to make Trondheim a better city to live and travel in.

Consultants said that,“ Our team members are not involved in formal meetings for UM, and we follow our UM independently based on our requirements ”.

We were responsible for safety management at the project level and strategic uncertainties. At the same time, the contractor was responsible for safety at the operational level.

For technical risks, we had regular meetings during the design phase with contractors and designers, and they were independent of design meetings. We recommend people use collective transportation more on heavy workdays in the project route to reduce the traffic in the area.

Project owner successfully managed neighbours (environmental factors) and land acquisition.

We are not involved specifically with UM in the design phase. But in new projects, it becomes common that consultants work with uncertainty systematically.

In Case 2 UM's meetings were conducted with sector authorities, municipalities, and owners. These meetings were evaluated positively, issues were highlighted, and the contractor could present various solutions (the contractor was responsible for the design). The contractor participated early in the project and gained ownership of solutions. Sector authorities had a positive impression of their cooperation. The support for UM in the project team by the organisation and top-level managers (both by owner and contractor) was confirmed. This support indicates a supportive culture of the organisation for UM practice and its importance.

We evaluated solutions (design alternatives) provided by the contractor, and according to their experience, prices, and track record, we chose them for this project.

Owners undertook their analyses personally and examined numerous facets of risks and alterations, and the contractor validated this cooperation. For instance, when they decided to make a design change, they consulted with designers, lawyers, and geotechnical engineers to analyse it from several angles: In an iterative process with the owner, the contractor made changes until the owner was satisfied with the result. The contractors have internal meetings informally (without a plan beforehand). The contractor focusses on operational risks, and the owner focusses on business-level risks. The contractor focusses on HES-related risks, operational risks and force majeure events.

We are not involved in the formal UM process, and we had only our internal UM, which focuses on our daily tasks.

The contractor was responsible for the project design. They confirmed information sharing with the owner, demonstrating the two actors' trust level.

4.2 The process component in the design phase

UM on Case 1 , based on the project owner's guidelines, are as follows: (1) defining goals and execution strategy; (2) identifying uncertainties; (3) qualitative evaluation; (4) quantitative assessments; (5) managing risks reducing consequences and sharing risk, transfer, insure against risk and accept (6) managing opportunities; (7) monitor and control and (8) communicating and reporting ( Veidirektoratet, 2011 ). This UM procedure was the same in both cases (1 and 2).

Regarding observed risks, resources are allocated, and actions are taken until the risks and consequences diminish. We are more concerned about risk than opportunities. The contractor said that we mainly focus on risks and consider opportunities but not as much as risks.

We have different uncertainties in our daily work which we decide and tackle daily and informally.

The project manager in Case 1 believes that the formal meeting for UM is held twice a year. However, the actual UM process is systematic and is conducted daily during the project because they believe all the problems they found during the design phase are somewhat related to uncertainties.

Case 1 's owner and consultants met with the railway authority to mitigate railway-related risks, indicating formal process and collaboration. The construction site is close to a heavily travelled roadway. In their qualitative risk assessment analysis, all risks were deemed acceptable, and a risk-mitigation strategy was developed for each risk item ( Sivalingam et al ., 2018 ).

In preparing the first proposal, we checked all the risks and opportunities and found construction client risks to know what changes we should make to achieve a specific price. We believe each project has its project-specific risks and opportunities; our focus was mostly on risks rather than opportunities.

Yes, but we perceive this as the contractor’s risk.” This negotiation happens during “bid evaluation” to accept the contract.

The above quote was an example of information exchange between owner and contractor and sharing risk during formal meetings. After delivering the design to the contractor, owners share less information with designers and consultants.

There is no clear line between ours and the owner’s risk. The contractor explained that they conducted an uncertainty analysis early in the bidding process. The design was delivered to the contractor completely, but they made changes during execution and presented their proposal to the owner.

Stemland et al. (2021) explained that the UM process included describing the planning area, identifying possible unexpected events, risk assessment and vulnerability, identifying measures to reduce risk and vulnerability and documenting the analysis and its effect on the project plan. In the zoning plan, design alternatives were defined and evaluated to choose the one with a lower possibility of risk for the project's goals.

Case 2 's project contractor stated during the interview that they were liable for the project's UM. Within the scope of his remit, the project manager is the decision-maker for addressing operational risks connected to progress and the economy. In Case 2 , the owner meets with the contractor every two weeks (confirmed by both parties) to assess risk and uncertainty jointly (formal UM process). The contractor must notify the client of the error before the deadline. Otherwise, the contractor (designer) should accept the risk of design flaws. Depending on the contract and risk category, the owner shares risks with a contractor. For instance, the ground condition is the owner's risk as other aspects of the contract's requirements.

The level of collaboration and information exchange with the owner was satisfactory, and all parties participated in meetings. We trust and the owner shares the risk register platform with us. But there exists less information sharing with consultants.

The day before discussions with the owner, we hold internal meetings and review newly detected risks or modifications to previously recognised concerns. Uncertainty is not a phenomenon we formally evaluate, but informally we evaluate it daily.

We were not actively involved in the uncertainty management process, and both owners and contractors were responsible for uncertainty management.

The document study also confirmed this. Contractors provide suggestions or new solutions to the owner for design and plan changes ( Værnes and Tunheim, 2019 ).

4.3 Tools and techniques component in the design phase

Document study and interviews of the Case 1 show that the owner uses a spreadsheet and uncertainty log for risk register, uncertainty analysis and UM. They utilised a tool called “Anslag 4.0” (translates to “estimates”) to calculate the road project's cost, including its uncertainty in different phases (quantitative tool). They have an economy follow-up system called “G-Prog project economics”. Both risks and opportunities can be logged and managed with this application ( Vegvesen, 2014 ). The owner in Case 1 stated,

“Tool's visualisation capabilities should be enhanced, and dealing with tools is somewhat complicated. The tools could provide somewhat precise answers, and track record of a successful project from a cost perspective shows this success. Tools are not resource demanding in comparison with project's cost, but it takes much time and energy to provide input data for the tool”.

We (contractor) have a system in the company which evaluates the risk and opportunity profile of the project before accepting it.” The system does not have high complexity.

As designers, we do not utilise the system that the owner and contractor use.

We documented project-related risks and opportunities in the system daily. We have a system for risk registering, and we use brainstorming to identify upcoming risks in the project’s design phase.

We utilized qualitative and quantitative tools, adding complexity to its understanding. We have a scoring system for each risk and determine its cost. The system we are using has some complexities in calculations and quantifications.” The tool is not resource-demanding compared to project cost and is easy to use, but feeding subjective data to the system could take some time and thinking.

They have various alternatives for projects, and they try to detail, evaluate and choose one of them. It's possible that, after selecting one alternative, they realised it was incorrect after more investigation. Case 2 document analysis and empirical findings demonstrated the contractor's early involvement in the project and ownership of the solutions. Sector authorities had a positive impression of this type of cooperation. They used a risk matrix for identifying risk relying on the owners' risk documents ( Stemland et al. , 2021 ). According to reports for the project's section, with high uncertainty and nearby the railway, the triple estimates of quantities and unit prices have been used as input values in the analysis. Consultants have included uncertainty factors in the analysis, and the results were obtained through Monte-Carlo Simulation. Both owner systems had good visualisation, allowing them to follow risk from red to green zone (safe areas). With visualisation, they can prepare reports on different dates and track changes.

Consultant's cost estimates were based on builders' and owners' estimates ( Sivalingam et al ., 2018 ). Based on empirical data, the consultant also fills out the project's risk matrix and sends it to the owner and an offer for the design competition. The owner's prepared forms of the risk matrix had no room for an opportunity register, and the focus was on the risks.

5. Discussion

First, we need to mention that the two project cases were similar in terms of operating country, culture, operation region and project type. In contrast, they had different owners. However, the final owner is the Ministry of Transport in Norway. Both projects were complex and large in absolute terms, but from a cost perspective the size of operations and timeframe were different. We investigated how uncertainties are identified and managed in the road projects' design phase. The literature study provided related criteria for essential components of UM in this study. Then through document study and interviews, this information evolved.

5.1 Uncertainty management in the design phase

In the design phase, actors prioritise clashes, most probably when they are suspected of following their agendas rather than general project objectives. The design process is a crucial linkage point between the expressed needs of the client and the actual realisation of the construction project. From one perspective, owners seek to avoid such extra cost and time (project outcome) as important parameters of UM and to have better solutions (design outcome) through an iterative design process. From another perspective, designers and consultants think long term. Better design means longer cooperation and more opportunities for future work. Therefore, it is a win–win game for all designers, contractors and project owners. Both cases' trust and collaboration levels could signify having a relationship between actors (a win–win game).

Both projects' owners and contractors follow a structured process for UM. They begin the process early and own the uncertainties at the strategic level, which needs competent people and efficient communication between actors. This implies on supportive organisational culture from UM process. For example, the owner accepts ground conditions or price increases (because of COVID-19 or unexpected events such as war) as uncertainty in the design phase early in the process. They know that after the design phase, the project manager might disclose ground conditions modifications that can add extra costs to the project. The owner considers contingencies for these types of uncertainties. Therefore, uncertainty ownership and supportive culture, such as management support, are important criteria in UM of the design phase. Qazi and Simsekler (2021) considered support for prioritising risks and assigning resources to critical risks as important criteria for the UM process.

5.2 Important criteria for uncertainty management framework in the design phase

We chose Johansen's (2015) framework as a theoretical framework. For each component [(a) human and organisation, (b) process and (c) tools and techniques)], some criteria were developed according to literature as relevant criteria for evaluating UM performance. These introduced criteria could not cover all criteria which show or measure UM performance. It is just starting point for knowing which criteria could be considered for UM to become successful in projects. This model was tested with empirical data to know how they play a role in the UM process in the design phase. Although for a better and more precise evaluation, it needs more data from different projects.

The selected criteria reveal the portion of the story. However, they cover significant ones. For instance, communication has been recognised as one of the essential components in humans and organisations. Notable is the fact that communication could be enhanced with better tools and competency. Therefore, these criteria are interconnected and are not independent of the UM process. Three important components also are interconnected in UM. For instance, a process with effective communication needs suitable infrastructure to support it. Owners who follow the formal UM process must have suitable systems and infrastructure to support such collaboration. Efficient UM and successful processes need to have competent people. They are not only independent components, but we could evaluate them independently. The overall performance of UM in projects depends on their performance collectively.

5.2.1 Criteria for human and organisation

Smith et al . (2006) stated that project owners and investors are risk-takers. Furthermore, the owner's function as a risk-taker by accepting risks related to ground conditions and strategic-level risks is consistent with empirical facts and theory. Although we can deduce that, if compensated, independent contractors may also be risk-takers. Risk-taking behaviour is comparable, but ownership is slightly greater in Case 2 due to the number of meetings and the owners' efforts to reduce risks. Being risk averse in group decisions of UM could be justified by the project's contract type, and a document study showed clear instructions by the owner for risk decisions in contracts ( Veidirektoratet, 2011 ). By choosing specific contract types, the owner and contractor try to avoid risks, so project stakeholders usually are risk averse, which is the typical trait of organisations in project execution because each party seeks their benefit and hidden agendas as stated by Lohne et al. , (2017) .

Workforce competency is a criterion that may be determined through performance, and their inclusion in this study was contingent on their years of experience and skills. Chapman and Ward's (2011) explanation regarding prerequisites for workforce competency based on personal skills and cooperation was approved through meeting documents and interviews with different stakeholders. Skilful people in related roles contribute to UM for each risk issue and uncertainty.

Effective communication and collaboration is reflected in meetings for design and tender competitions before and after contracting, and it could change amongst stakeholders according to empirical data. For example, at the beginning of the design process, the consultants' role is chromatic, but later it could fade or reduce as contractors play the major roles in UM in the design phase. Osipova (2007) demonstrated contractors' significant level of participation and collaboration in UM and the low level of communication and participation by consultants. Chapman (1999) also confirms that efficient management in the design phase needs clear and effective communication. This implies that road projects should consider the designers' role as essential and actively participate in the UM process. This could impose extra costs on the owner, but on another side it could make the consultant and owner closer to each other instead of the contractor who has a mediator role.

Collaborative relations of stakeholders were evident in both cases and affirmed the theory about the necessity of effective communication and collaboration during the project's design phase ( Osipova, 2007 ; Aslam et al. , 2019 ). Besides, using competent people for UM and RM was strongly confirmed according to empirical data. In both cases, budgetary performance was one of the criteria for choosing consultants and contractors. Adafin et al. (2021) 's research show how workforce competency in the budgetary analysis of projects in the design phase could be a risk factor. For example, the competency of consultants, information flow and experience of the project team are risk factors that influence clients' costs. Based on interviews, we recognised these factors introduced by Adafin et al. (2021) strongly confirmed.

5.2.2 Criteria for the process of uncertainty management

Norwegian quality assurance systems for large road projects require quality checks and documentation before financing, which is in the design phase. In both cases, project managers follow the parent organisation's guidelines and instructions. Rashid and Boussabiane (2021) found that project organisational culture influences RM motivations and processes.

The owners implied the formal UM process in both projects. This trend is in coordination with the literature about the necessity of formal UM in projects by Simister (2004) and Johansen (2015) and less participation of consultants. Along with this formal process led by the owners, the informal UM process was noticed by the owners, contractors and consultants working on the project. The design process is iterative and needs helpful information sharing with consultants and contractors. Krane and Langlo (2010) indicated the necessity of having an informal process of UM for project success that serves as a supplement to the formal process; any policy by the owner or limitation in sharing necessary information for design could affect the final result. Empirical findings conform to Osipova (2008) , which found that effective communication and trust support open discussion about project risk. The informal UM process could be improved by having trust and a culture that supports open communication and information sharing in the project. Karlsen (2011) introduced UM culture with openness, respect and a positive attitude.

The ability of companies to prioritise risks and opportunities in both cases depends on their experience and the competent people they use in their UM process. To some extent, stakeholders can have conflict because of the subjective nature of project risks and opportunities, according to Johansen (2015) and Qazi and Simsekler (2021) .

Collaboration levels of actors in UM practices could be a reason for their benefit from the project. For example, it is hard to expect consultants with less project benefit to participating formally in UM unless their contract obliges them to do that or have benefits. Contractors and owners benefit from this cooperation, and reducing their role in this process is inevitable. However, the strategy and effort they put into effect could depend on the risk levels. Operational-level risk is more the concern of the contractors' project managers, and their effort during the projects' design is expected compared to the owner. Communication level and information exchange between designer and owner change after design delivery to owner or contractor.

5.2.3 Criteria for tools and techniques in the uncertainty management process

Both cases have difficult-to-measure criteria. One of them was the preciseness of tools and techniques. Tools have quantitative input, and results might be considered more precise than qualitative ones. Smith et al. (2006) explained that computers with high complexity in models need fewer manual calculations and the accuracy increases but complexity increases. In contrast, UM in road projects based on empirical data relies somewhat on the subjective judgement, which might increase manual calculations and reduce accuracy. Competency and experience could play an important role and could reduce deviation from actual costs. Austeng et al. (2005b) say tool preciseness depends on how detailed the UM is. In both cases, based on a document study ( Vegvesen, 2014 ) and interviews, the owner defined acceptance criteria for calculating uncertainty and risks in all project phases. A high level of detailing capability, such as a long list of uncertainties and defined measures for tackling uncertainties, are samples for the tools' detailed level. There exists discussion about to what extent such detailing is helpful and improves work efficiency or is preventive. There were some voices from interviewees about the capacity for improving the visualisation capability for better management of the long list of uncertainties in missing some uncertainties.

UM tools utilised in large projects outweigh their costs but, from time and energy perspectives, are resource demanding. When it takes much time to prepare input data to model, the result is expected to be accurate. Therefore, there is a direct relation between tool preciseness and cost. According to Smith et al . (2006) , computer systems make such analysis easier and facilitate visualisation. This capability depends on parent organisation support, the process and defined specifications for project UM. Case 2 exploited “web-based tools” which provide better visualisation capability. In Case 1 , empirical data demonstrated visualisation needs for improvement. Dikmen et al. (2012) pointed out that web-based tools provide better visualisation and documentation capability as confirmed by empirical data with high documentation capability. The Norwegian projects had pre-requirements for a demanding level of documentation.

5.3 Practical implications of the research

Project evaluations showed that the choice of skilled people, UM process and suitable tools and techniques for UM depends on the projects' characteristics, stakeholders' collaboration level and owner company's organisational variation. High uncertainty in design influences the contracts strategy of the projects, and they made a competition for a design to find the best solution. For example, having a project constructed inside the city with existing uncertainties and a symbolic structure affects the city from aesthetic dimensions. Furthermore, it directs the owners towards design competition to get a better bridge design result before the project's construction.

In contrast, a large-scale project with long roads and long-time frames with different tunnels and bridges outside the city could direct the owner to involve in more collaborative participation and choose the main contractor with high experience in managing different contractors. Trust could be an influencing factor in such collaboration to monitor the work in all phases and overall have better control over the project. The risk manager in Case 2 also confirmed this collaboration as an open and satisfying relationship (trust). These empirical data were in coordination with Osipova's (2008) findings, which show that an open attitude, effective communication and information exchange supports project risk. According to Karlsen (2011) organisation culture influences and determines the effectiveness of UM.

When there is a collaborative contract between owner and contractor, they share more information and use integrated systems for UM. For example, the study of Case 2 shows more information sharing in risks and uncertainties and having integrated systems in which both sides have access to the system. The integration level in Case 1 was less than in Case 2 . When needed, information sharing and collaboration levels can signify trust between owners and contractors. Generally, designers have less information sharing of uncertainties with contractors and owners, which Osipova (2007) in the research confirm the low collaboration of consultants in UM process.

Identified criteria in the paper gave a better insight to practitioners, project managers, owners and policy-makers in the UM process and evaluation of it in the design phase. Project managers will notice criteria such as effective communication, web-based tools, better documentation, visualisation capability and sharing information as important criteria which are interconnected and are important for the design phase. Owners know that early information sharing with designers leads to better product design. The benefits of better design directly are for project owners who will experience lower changes and higher value (fewer cost overruns). For contractors, based on contract type, the result could be different. Policy-makers would comprehend the significance of the design phase and define stringent requirements for projects to pass quality checks. They have an integrated approach with a special focus on UM process, standard tools (such as web-based tools or documentation standards) and important uncertainties (such as ground conditions and market conditions). Quality checks in the design phase enhance road project performance during execution, which directly benefits society.

In this paper, we tried to fill this gap in the literature by developing Johansen's (2015) , framework by identifying relevant criteria for measuring UM in the design phase. For instance, Xiahou et al. (2022) mentioned that existing research mostly notices post-accident management, and there is a shortage in pre-management awareness. Therefore, with better pre-measurement, we could expect a better design process with fewer changes and redundant work later. This pre-measurement in the design phase is essential for successful project execution and achieving a better result with lower consequences for unexpected or expected ambiguities, variations and uncertainties. For instance, effective communication, better visual capabilities, information sharing and efficient documentation in the design process lead to better product design.

6. Conclusion and further work

This paper aimed to improve knowledge about key components of UM. The case study approach contributed to getting a deep analysis of these components. Johansens' (2015) framework with identified relevant criteria was evaluated using empirical data. According to the literature review, we grasped some relevant criteria for each component. Relevant criteria are used for assessing UM in the road projects' design phase. Two RQs were answered in this paper as follows.

First, the design phase is a process in which designers have an essential role in delivering the project design. Project designers seem less involved in the formal UM process and use fewer necessary tools than owners and contractors. It seems logical that people are involved in a process based on their perceived risk. Owners mainly focussed on strategic uncertainties, and contractors focussed on technical and operational uncertainties related to design and constructability. Collaboration was strong between contractors and owners. For a successful risk and opportunity management process, all stakeholders must collaborate, which relies on a culture of efficient UM. Therefore, designers must have more formal involvement in the UM process than today as Osipova (2008) reminded the important role of consultants in the design phase. Both cases had different owners and consultants, but the designers' involvement in the formal UM process for both projects was low.

Second, we used triangles of “human and organisation”, “process” and “tools and techniques” that need to work together. According to relevant criteria from the literature, we recognised these criteria in both cases and how these criteria function in both cases. For instance, competent people and supportive culture are needed to better communicate and share information from tools and techniques.

In conclusion, despite limitations, this research presents guidelines for road projects concerning the UM in the design phase and its measurement. For this purpose, project owners should notice a culture of trust and senior managers' trust in the design phase. Having a trusting culture contributes to open communication and information sharing. Effective communication and information sharing also need better tools with visualisation capability and documentation, besides the involvement of all parties and consultants in the formal UM process. All the criteria are interrelated and should work together for a successful UM.

This study provides a holistic view of the important components of UM [(a) process, (b) human and organisation and (c) tools and techniques)] by providing an explicit overview of their important criteria and role in each component. Evaluating these components and following them in the later phases could give insight to practitioners, project managers, owners and policy-makers in the UM process and evaluation of it in the design phase. They will learn about the quality of the UM processes, applied methods and tools in each case and the differences between the two cases. Future studies will develop this qualitative evaluation by using a quantitative approach. Evaluation of criteria in three aspects is subjective and needs to be completed by survey-based quantitative evaluation to become precise. For instance, determining the tools' complexity level, user-friendliness or documentation level could be conducted by experts' analysis through a questionnaire.

Public construction projects' stage gate model

Uncertainty management framework with three components

Characteristics of cases for investigation

The process of literature review in this paper

List of documents which has been studied in this paper

Interview process

Appendix Summary of findings based on relevant criteria for two cases

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Acknowledgements

The authors extend gratitude for the collaboration of Norwegian Public Road Administration and Nye Veier AS for providing the opportunity for interviews.

Corresponding author

About the authors.

Rouzbeh Shabani is PhD candidate in project management at Norwegian University of Science and technology (NTNU). He has published some articles in decision-making and project management. He has worked with many companies in the Information Technology (IT), construction, oil and banking industry. Now he is working on uncertainties in different phases of road construction projects.

Tobias Malvik is PhD candidate in project management at NTNU. He has published articles in international journals and conference proceedings. The focus of his current and recent research has been in the domains of uncertainty management, Lean Construction, project delivery methods and collaboration.

Agnar Johansen is Professor in Project Management at the Department of Civil and Environmental Engineering at NTNU. He has more than 20 years of experience as a researcher, teaching and consultants – in the public and private sector. He has been the project manager for a large research project focussing on uncertainty management, time management and urban development in smart cities. Johansen has been general manager for Norwegian Centre of Project Management (NSP) for 4 years and he is currently the leader for Centre for green built environment at NTNU. He published many books and more than 100 papers in the field of project management and sustainable leadership of projects.

Associate professor Olav Torp has over 25 years' experience with research and teaching in the field of project management at the department of Civil and Environmental Engineering at NTNU. He published many books and articles in the field of uncertainty management, cost analysis and development in construction projects. Torp has worked with companies, especially Norwegian agencies within the topic of uncertainty analysis of the project's costs. He has facilitated and participated in a large number of uncertainty analysis processes, development of theoretical frameworks and methods within uncertainty analysis and management. Torp has been a supervisor for specialisation projects' and master's theses of students for long time.

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Three safety criteria for evaluating curved roadway sections including transition sections were analyzed in order to address these important target areas for reducing accident frequency and severity. These criteria are (a) achieving consistency between successive design elements ; (b) harmonizing design speed and operating speed, especially on wet pavements ; and (c) providing adequate dynamic safety of driving. The above safety criteria constitute the core of the overall safety module proposed in this study for classifying road networks or roadway sections (or both), existing or planned, as good, fair, or poor designs. The evaluation process of the safety module, encompassing separate evaluation processes for each of the above safety criteria as well as for the combination of all three criteria, can be done manually by using the Geographic Information System known as SPANS. By using discriminating colors or symbols with SPANS, the resulting separate or combined design safety levels...

Transportation Research Procedia

Flavia De Simone

CETRA 2014, 3rd International Conference on Road and Rail Infrastructure 28–30 April 2014, Split, Croatia

Florentina-Alina Burlacu

Improving road safety has been the key objective for road authorities worldwide for the last years. Lately, many concepts were adopted to reduce the number of fatalities, concepts like self-explaining roads, low cost measures or forgiving roads. As new research findings are published, differing theories evolve and road safety visions change. Nowadays, around 30% of accidents on the entire EU road network are caused by inadequate infrastructure. The way roads are laid out and designed can reduce the exposure to traffic of vulnerable road users, reduce the probability that crash and injury occur when these users are exposed and reduce the severity of injury if it occurs. Substantial and sustainable casualty reductions can be achieved in relatively short time and at relatively short cost by identifying and treating high risk infrastructure sites, creating safer and forgiving roads. The aim of this paper is to improve traffic safety by increasing the awareness of road authorities, in order for them to implement road safety measures following the concepts of forgiving roadsides and taking into consideration the human factors also.

Mate Gjorgjievski

IRJET Journal

Transport infrastructure plays a vital role in the economy, the presence of quality of road infrastructure. India has one of the largest road networks with about 47 lakh km. of roads. The total expenditure is estimated at Rs. 64,900 crores in (2017-18) allocations for road infrastructure. This is 24% higher than the revised estimates for (2016-17). Highest allocation towards roads and bridges at 63%, this is towards the allocation of national highways authority of India. The requirement of safety measures and traffic signs are very necessary on the roads for safe and efficient movement of traffic, but before it the road conditions also plays a vital role. The road infrastructure should be well planned. The study focuses on the requirements of road infrastructure that should be adopted at national highway that connects with many other local roads while passing the city area. The vehicular survey is to be done which will decide the road LOS (level of service) and vehicle volume count. Then there will be design the traffic lights and safety measures at the required points. New roads are planned, designed and operated according to safety standards such as: Provide safe road infrastructure for all road users, Accessible and safe pedestrian overpass and underpass in risky areas. The process used to conduct such kind of study included lumpsum of traffic police data, making interaction with the people in order to known perspective of the people towards safety and also making close watch for fleet and pedestrian turn around.

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Literature Review on Chassis Design of On-Road Heavy Vehicles

• K. Rajasekar , R. Saravanan
• Published 2014
• Engineering

11 Citations

Stability analysis of chassis structure in heavy load carrying vehicles, design and structural analysis of truck frame, stress analysis of ladder chassis with various cross sections, development of electric vehicle (ev)-bus chassis with reverse engineering method using static analysis, design optimisation and analysis of an all-terrain vehicle chassis with balance rocker suspension-ijaerd, development of electric vehicle (ev)-bus chassis with reverse engineering method using static analysis, design, development and analysis of self-balancing electric bike, determination of dynamic loading of bearing structures of freight wagons with actual dimensions, optimum redesign of an agricultural water bowser, an overview of the role of composites in the application of lightweight body parts and their environmental impact: review, 13 references, statics and dynamics structural analysis of a 4.5 ton truck chassis, truck chassis structural thickness optimization with the help of finite element technique, structural analysis of automotive chassis frame and design modification for weight reduction, stress analysis of a truck chassis with riveted joints, numerical and experimental investigation on stochastic dynamic load of a heavy duty vehicle, design and evaluation of a unified chassis control system for rollover prevention and vehicle stability improvement on a virtual test track, experimental analysis and quasi-static numerical idealization of dynamic stresses on a heavy truck chassis frame assembly, stress analysis of heavy duty truck chassis as a preliminary data for its fatigue life prediction using fem, failure investigation and stress analysis of a longitudinal stringer of an automobile chassis, of achievements in materials and manufacturing engineering triz method for light weight bus body structure design, related papers.

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A comprehensive review: multisensory and cross-cultural approaches to driver emotion modulation in vehicle systems.

Featured Application

1. introduction.

• Correlate the evidence on drivers’ emotions and behaviors during the driving process: Analyze driving behaviors under various emotional states. Assess the impact of different emotional conditions and driving behaviors on the risk of road accidents.
• Examine the impact of driver emotion modulation methods on drivers’ emotions based on unisensory and multisensory inputs: Evaluate the effects of single-sensory stimuli, such as auditory and visual inputs, on drivers’ emotional regulation. Use psychological questionnaires, physiological metrics, or neural activity as assessment tools. Assess the outcomes of multisensory stimuli, specifically the combination of auditory and visual elements, on emotional regulation. Compare the differences between single-sensory and multisensory approaches. Analyze emotional state variations using pre- and post-intervention measurements.
• Identify driver emotion modulation from a cross-cultural adaptation perspective: Examine the effectiveness of emotional regulation methods across diverse cultural contexts. Analyze whether emotional regulation strategies, such as cognitive reappraisal, emotional expression, and sensory input, require adaptation in various cultural settings. Employ experimental findings and statistical analyses as evaluative criteria.

2.1. Information Retrieval Tactics and Eligibility Criteria

• Articles were published after 2018, with most published within the past five years, and some found from the list of references in the relevant literature.
• Articles were selected by conducting literature searches in Web of Science, Scopus, and Google Scholar.
• The following keywords were used for the literature search: “driver emotion modulation”, “driver emotion regulation”, “driver behavior”, “driver style”, “driver safety”, “driver emotion”, and “cross-cultural impact on driving emotion”.
• The search strategies were compiled and the literature search was conducted using the Boolean operators “AND” and “OR”, such that “driver emotion” AND “modulation” OR “cross-cultural impact” were used in the search engine.
• The findings from the literature search were examined. The Web of Science database returned 380 articles, while the Scopus databases returned 460 articles.
• Articles obtained from the Web of Science and Scopus databases were combined. Articles were collected using CiteSpace-6.3.1 software, which eliminates irrelevant references and duplicates. The number of articles was reduced from 840 to 802.

2.2. Data Analysis

• Analysis of overall findings: The data trends from the 802 articles were visualized using CiteSpace software. The procedure for data analysis is described below. First, we keyed the full records in plain-text format into CiteSpace software. Next, we set the parameters, including time slicing, year span (from 2018 to 2023), and years per slice (1 year) for country and keyword analyses. We then employed the CiteSpace software and obtained the networks and data, obtaining the countries and keywords. We also obtained the data of grants used to cluster the keywords and countries. Finally, we conducted keyword co-occurrence analysis and presented the visualization results. We set a g-index of 20 (k = 20) to ensure the selected literature demonstrated significant citation impact while controlling for node numbers to exclude irrelevant articles. A higher g-index indicates greater influence of the literature within the citation network. However, a higher g-index increases the number of nodes, indicating more irrelevant literature [ 38 ]. We excluded articles with low citations, minor influence, and limited clustering relevance, allowing for a focused analysis of works that make substantial contributions to the field. The number of articles selected after screening of the most relevant articles and keywords was 277.
• Analysis of specific findings: These 277 articles were then assessed by two reviewers to identify the articles with the most relevant themes along with supplementary content from Google Scholar. The articles were reviewed by two independent reviewers who are not co-authors of this manuscript to avoid any potential bias. The reviewers are experts in automotive technology studies. At this stage, each result was reviewed, and the search results were refined by retaining articles related to driver behavior and emotion regulation, cross-cultural adaptation, and sensory input in driver emotion modulation. The criteria for excluding articles included the following: relevance to the research questions and objectives; methodological rigor and quality of the data; and a high impact factor of the journals to ensure credibility. Each full text was evaluated based on the exclusion criteria shown in Figure 1 . It was ensured that the selected literature not only had a high impact in terms of citations, but was also closely related to our research topic. The remaining articles after peer review were categorized as follows: (1) driver emotion and behavior (13 articles), driver emotion modulation based on unisensory and multisensory inputs (34 articles), and cross-cultural impact on drivers’ emotions (27 articles).

3.1. Overall Findings

3.2. specific findings, 3.2.1. driver emotion and behavior, 3.2.2. driver emotion modulation based on unisensory and multisensory inputs, 3.2.3. cross-cultural impact on drivers’ emotions.

• Cultural Background Differences
• Influence of culture on driver emotion modulation
• Influence of human characteristics on driver emotion modulation

4. Discussion

4.1. strengths of the studies reviewed in this article.

• The number of articles published on emotion modulation has been progressively increasing over the years, increasing from 80 in 2018 to 160 in 2023.
• A large number of participants were involved in the studies reviewed in this article, many of whom joined experiments that helped guide the research in the right direction.
• There is a special focus on the effects of driver emotion modulation on driving safety. Studies have shown that individual differences mean that drivers respond differently to sensory inputs, highlighting the importance of personalized approaches.
• Cultural backgrounds have been found to influence how drivers perceive and react to different sensory inputs. For example, the interpretation of colors in visual interfaces, the type of music considered soothing, or the acceptance of voice commands can vary widely across cultures.
• Human-centered approaches to driver emotion modulation are increasingly focused on enhancing user experience by aligning in-vehicle communication and attention management with drivers’ preferences and traits. Autonomous vehicles will increasingly use non-invasive technology to enhance safety and necessitate adaptable, culturally sensitive systems, as mentioned by [ 103 ].

4.2. Weaknesses of the Studies Reviewed in This Article

• Selection bias: The data for this review were sourced from two databases, Web of Science and Scopus. While these databases cover a broad range of content, they do not encompass all publications.
• Language bias: Limiting the review to studies published in certain languages (typically English) may overlook important research conducted in other languages, potentially skewing the results of the review.
• Geographic bias: The studies included in this review are primarily concentrated in specific countries in Asia and Europe (such as China, Japan, the USA, and the UK), which could narrow the scope of the research findings.
• Limited focus on emotion types: There is a predominant focus on unpleasant emotions, without correlating different categories of emotions with specific driving behaviors.
• Unisensory driver emotion modulation: Driver emotion modulation is often conducted based on a single sensory input, lacking effective emotion modulation strategies.
• Cultural studies from a social science perspective: The cross-cultural impact on drivers’ emotions is predominantly studied from a social science perspective, without considering driver emotion modulation from a multicultural viewpoint to address global cultural developments.
• Insufficient human-centered studies: There is a paucity of studies on individual differences in drivers’ emotional responses and sensory preferences, which are crucial for tailoring interventions.

4.3. Opportunity Analysis

• Develop integrated multisensory systems that combine visual, auditory, haptic, and olfactory modalities. Emphasize the use of empathetic voice strategies and music to alleviate negative emotions and enhance trust, while leveraging olfactory notifications to improve mood and behavior with minimal distraction.
• Transition vehicle environments from purely functional to multisensory spaces, incorporating a variety of sensory inputs to create a more engaging and emotionally supportive driving experience.
• Tailor emotion modulation interfaces to accommodate cultural preferences. For instance, in collectivist cultures like those in Asia, employ auditory cues and symbols more extensively, given this population’s higher sensitivity to sound and preference for symbolic communication.
• For individualistic Western cultures, design clear, low-context verbal guides and focus on focal visual elements. Utilize abbreviations and direct expressions to cater to their communication styles and visual sensitivity.
• Implement advanced emotion recognition systems that can accurately detect subtle emotional cues, especially in cultures where emotional expression is more restrained, such as in many Asian countries. This will enable more precise and effective emotion regulation interventions.
• Develop adaptive technologies that can modify their emotion modulation strategies based on the user’s cultural background. This includes customizing voice interactions, interface designs, and feedback mechanisms to align with diverse cultural norms and values.
• Examine the influence of cultural exposure on drivers’ emotions and incorporate this understanding into the design of emotion modulation systems. Recognize that drivers with significant exposure to new cultures may have different emotional responses and needs.

4.4. Threat Analysis

5. conclusions, author contributions, data availability statement, acknowledgments, conflicts of interest.

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Share and Cite

Zhang, J.; Raja Ghazilla, R.A.B.; Yap, H.J.; Gan, W.Y. A Comprehensive Review: Multisensory and Cross-Cultural Approaches to Driver Emotion Modulation in Vehicle Systems. Appl. Sci. 2024 , 14 , 6819. https://doi.org/10.3390/app14156819

Zhang J, Raja Ghazilla RAB, Yap HJ, Gan WY. A Comprehensive Review: Multisensory and Cross-Cultural Approaches to Driver Emotion Modulation in Vehicle Systems. Applied Sciences . 2024; 14(15):6819. https://doi.org/10.3390/app14156819

Zhang, Jieshu, Raja Ariffin Bin Raja Ghazilla, Hwa Jen Yap, and Woun Yoong Gan. 2024. "A Comprehensive Review: Multisensory and Cross-Cultural Approaches to Driver Emotion Modulation in Vehicle Systems" Applied Sciences 14, no. 15: 6819. https://doi.org/10.3390/app14156819

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2024 Yezdi Adventure Review; Lighter, Nimbler & Much Improved

The yezdi adventure now becomes significantly better than before, both on and off the road. here's a quick lowdown of what all changes on the motorcycle and what becomes better..

The Yezdi Adventure now becomes more fun to ride than before

Launched in 2022, this is the second instance of the Yezdi Adventure getting an update. And this time around, the motorcycle becomes what it should have always been. While the updates are subtle, the sum total of them all makes the bike lighter and much improved. We spent a day riding the updated Yezdi Adventure at Pro Dirt Adventure on the outskirts of Pune, with more focus on going off-road and getting caked in mud and slush from head to toe.

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Also Read: 2024 Yezdi Adventure Launched In India

Yezdi Adventure: Design

Not much changes in terms of design on the motorcycle. The graphics on the fuel tank are new and the metal frame now gets an 'estd 69' stickering, which was the year in which Yezdi was established. There are four new colour schemes on offer - Glacier White, Magnite Maroon, Wolf Grey and Tornado Black. The overall design and silhouette of the motorcycle stays the same as before but there's this sense of the motorcycle becoming leaner and meaner.

Also Read: Yezdi Adventure Now Can Be Bought With Mountain Pack 

Yezdi Adventure: Changes

To start with, the motorcycle now becomes 4.5 kg lighter. While the motorcycle by itself loses just 1 kg, the metal tank guard is now lighter by 3.5 kg. The motorcycle weighs in at 187 kg now. And the spring in the Yezdi's step is apparent too. The exhaust port has been rerouted through the centre for better heat management and efficiency but that needs to be tested on a hot summer day rather than a balmy rainy day with the temperature in mid-twenties. 

The other reasons for the motorcycle feeling easier to ride is because the suspension is re-calibrated, the seat cushioning becomes comfier and the gear ratios are remapped for better torque delivery in the bottom end and in the mid-range as well.

Yezdi Adventure: Specifications

The engine gets a few tweaks as well to make it run smoother and sharper. Yezdi calls it Alpha 2, where the '2' stands for second generation. While the architecture stays the same, there is no change to the displacement. The liquid-cooled motor now makes 29.68 bhp which is around 0.6 bhp lesser than before. But the torque output stays the same at 29.84 Nm.

Yezdi Adventure: Performance

Back to the spring in the step of the Yezdi Adventure, there is an apparent ease of operating the clutch, brakes and the throttle, that the older model was missing. But there was a hiccup too. Quite a few of the test motorcycles with other journalists and the one with yours truly too, was giving problems during a cold start. Having said that, the motorcycle is better equipped to deal with daily commutes thanks to a stronger shove at the bottom end.

The engine feels peppier and rev happy, egging the rider on to rush through the gears and building up speed quickly. The brakes could have had a stronger bite but there is a case for a dull bite from the brakes as most of us spent the day ripping through trails.

Yezdi Adventure: Off-Road Performance

The motorcycle loses some of its top-heaviness and feels more neutral and balanced around a corner and the re-tuned suspension does a better job of absorbing bumps, particularly at low speeds. And even on high-speed runs on rocky terrain, the motorcycle feels more stable and manageable than before, thanks to the weight reduction and the change in the centre of gravity. 

The 21-inch/19-inch setup continues as before and while the original equipment tyres do a good job on and off the road, but they will need to be changed if you like your off-road excursions to be a little more hard-core. Truth be told, it is close to the Royal Enfield Himalayan 450 in its off-road capabilities, closer than you would imagine.

Yezdi Adventure: Features 

The feature set stays the same, with the motorcycle getting Bluetooth connectivity, turn-by-turn navigation and three settings for the ABS - road, rain and off-road. In the off-road mode, the ABS on the rear wheel can be fully disconnected. Yezdi offers a variety of accessories with the motorcycle as well.

Yezdi Adventure: Verdict

Now the Yezdi Adventure, it gets a significant bump up as far as the riding experience is concerned. The changes are incremental and have been made after listening to feedback from the customers. In addition to the updates, Yezdi reduced the price of the Adventure by Rs. 5,000. The prices now start from Rs. 2.10 lakh and go up to Rs. 2.20 lakh. It is easy to recommend the Yezdi Adventure for those who are in the market for a motorcycle between 300 to 500 cc and price less than Rs. 2.5 lakh. The ADV now makes a strong case for itself if you are in the market for getting the 'one motorcycle that does it all' and on a pocket-friendly budget.

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Arzopa Z1RC 2.5K Portable Monitor review: Productivity on the go

Working from home means being able to log in from anywhere — that’s what I love about it. But it’s tough to get fully comfortable when working out of hotel rooms or relatives’ homes. That’s where a portable monitor can help, since you can create an office wherever you are. I tested the Arzopa Z1RC Portable Monitor and found it makes working away from home a breeze, with clear definition and accurate colors. Read the rest of my Arzopa Z1RC 2.5K Portable Monitor review to find out if it’s a good fit for your needs.

Arzopa Z1RC 2.5K Portable Monitor

Unboxing and first impressions of the arzopa z1rc 2.5k portable monitor.

The Arzopa Z1RC arrived securely, packed with brown paper wrapping. It was packed tightly inside its own sealed white box bearing the laptop’s branding.

In the box, I found the following:

• Arzopa Z1RC monitor.
• USB-C to USB-C cable.
• USB-C to USB-A cable.
• Mini HDMI to HDMI cable.
• Brief user guide.
• Warranty card.

The user guide relies completely on diagrams to walk you through which cables to use to connect the monitor to various devices. You can connect to desktops, laptops, phones and gaming consoles. You can also find an in-depth connection guide on the Arzopa website.

Right out of the box, I was impressed with the Z1RC. For such a lightweight product, it’s surprisingly high quality. The bezel is thin to maximize screen space, and the stand tucks easily into the back of the monitor to keep the device compact while you’re transporting it. The stand can be adjusted to find the perfect viewing angle.

Setup was surprisingly easy. I set the monitor on my desk, grabbed the USB-C-to-USB-C cable and plugged one end into my laptop and the other into the monitor. My desktop wallpaper appeared on the monitor within a few seconds.

Arzopa gives you three options:

• Extend your desktop across two screens.
• Duplicate your desktop, creating a second monitor with an identical view.
• Put your device screen to sleep and show the image on the portable monitor only.

You can customize your views in a variety of ways, both through using the controls built into the monitor and the display settings on your device. Allow plenty of time to get your monitor set up the way you like it before you need it.

• Affordable.
• Easy setup.
• Crisp, colorful display.
• Special cable needed for most iPhones.
• Slow refresh rate.
• No case provided.

Key specifications:

• Product name: Arzopa Z1RC.
• Screen size: 16 inches.
• Panel type: IPS.
• Aspect ratio: 16:10.
• Resolution: 2560 x 1600.
• Display color: 1.07G.
• Color temperature: 6800K.
• Visual angle: H: 85°/85°Min V: 85°/85°Min.
• Contrast ratio: 1200:1.
• Brightness: 500cd/m2.
• Color gamut: 100%.
• Input interface: Mini HD and Type-C full function.
• Speaker: Two built-in 1-watt speakers.
• Refresh rate: 60Hz.
• Dimensions: 14 inches long x 9.3 inches high x 0.36 inches wide.
• Weight: 1.7 pounds.
• Compatibility: PC, Mac, Android and iOS phones, PS5, Xbox, Switch and Steam Deck.
• Price on publish: $119.99.

Key features of the Arzopa Z1RC 2.5K Portable Monitor

Crisp display.

The crispness of the Arzopa Z1RC’s display surprised me, especially when compared with more expensive portable monitors. You’ll get a QHD 2.5K IPS LCD display with 100% color gamut, making this monitor excellent for standard everyday use and decent for gaming. It falls short when compared to the type of gaming monitors used at home, but for gaming on the go, it works fine.

I was initially disappointed that the display was so dark, but found a brightness button located on the left side of the monitor. The onscreen display button just above it brings up a menu where you can adjust the contrast, resolution and more.

Compatibility

You’ll find a long list of compatible models on the Arzopa Z1RC product page, but if you have a PC, Mac or phone, chances are, it’s compatible. This monitor also works with a wide range of gaming consoles, including Switch, XBOX, PS3, PS4 and PS5.

This monitor connected without issue to my 2022 MacBook Pro, but when I tried to connect my just-purchased iPhone 14, it was a no-go. Apple didn’t upgrade to the USB-C until the iPhone 15, so if you have an older model, you’ll need to purchase a USB-C to Lightning cable to use your iPhone with this model.

USB-C to Lightning cable

Before purchasing, my hot tip is to check the ports on your devices and make sure the included cables will cover you. That way, you’ll be able to use your monitor as soon as it arrives, rather than having to track down accessories and wait for them to ship.

Portability

Weighing only 1.7 pounds, the Z1RC is lightweight and easy to transport. It’s also only 0.3 inches thick, so you can easily carry it inside a laptop bag or larger backpack.

One downside to the monitor being so lightweight is that they don’t stand up well on softer surfaces. When I’m in a hotel room, I prefer to sit on a bed rather than squeezing into those lackluster desks, and the monitor doesn’t balance so well on a bed. If you plan to always sit at a desk or table, though, that won’t be an issue for you.

The Arzopa Z1RC isn’t particularly rugged, so you’ll need to be careful with it. Since it doesn’t come with a case, you’ll likely want to invest in one, although if you have a separate section in your laptop bag, you could slide this monitor in there. The key is to prevent the screen from getting scratched.

The case holding the screen is a metal alloy, so you’ll get decent durability. The stand tucks handily into the back of the monitor, but it does feel a little flimsy. If you forget to snap it back into place before transporting the monitor, the stand could be at risk of breaking off. The good news is, you can buy a protective sleeve for less than $25.

Arzopa 16.1" Portable Monitor Sleeve Bag

Performance, refresh rate.

If you’re a gamer, pay close attention to the refresh rate on this monitor — it’s only 60Hz, which might not give you the responsiveness you need. You may be willing to sacrifice a little power for the convenience of gaming on the road, though.

For me, a 60Hz refresh rate is perfectly fine. Yes, I might want to watch a little Netflix while I’m traveling, but so far, video has been fine. If you’re using the monitor for business apps or basic surfing, the refresh rate should be more than sufficient.

Arzopa’s portable monitors come with built-in speakers, but I have to admit, I have no use for them. I’d rely on the audio from my laptop if I didn’t typically have AirPods in my ears. One weakness of most of these monitors is that they lack Bluetooth compatibility, so if you want to connect wirelessly to speakers or accessories like gaming headsets and gaming mice , you’ll need to connect those to your computer.

All that said, the audio output is comparable to what you get with your laptop or phone’s speakers. This monitor features two built-in speakers, each bringing 1 watt of power.

The color range of this portable monitor is impressive, but again, it falls short when compared to a standard monitor. You’ll get 8-bit + 2FRC/1.07b with 500 nits of brightness and a contrast ratio of 1200:1. In other words, this monitor packs a punch when it comes to its display, but that’s speaking specifically about portable monitors. Standard desktop monitors will bring better performance, but you can’t easily tuck those into your backpack and take them on the road with you.

With this monitor, you get a professional, streamlined design that will blend in with any environment. I personally liked the slimmer bezel since it puts the emphasis on the screen rather than wasting valuable space. I would prefer that the buttons were a little better marked, but the user guide made the functionality of each button clear, so there was just a brief learning curve.

Is it for you?

If you prefer to work with dual screens, or even a large monitor rather than the one built into your laptop, the Z1RC might be a great choice. The lower price point means that even if you only use it occasionally, it will be well worth it. If you’re like me, though, and rarely use multiple screens, this monitor might not be all that useful for you. This model can also work for gamers who need a monitor to go with their consoles. If you’re buying it for gaming, though, a portable monitor with a higher refresh rate will probably be a better fit.

User reviews

Users praise the Z1RC’s display, loving its vivid colors and crisp clarity. They also like how lightweight it is, as well as the convenience of being able to charge it off a laptop. Some say the colors vary slightly from their home monitor, with one user describing the colors on the Arzopa Z1RC as warmer.

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Arzopa Z1RC 2.5K Portable Monitor alternatives

Arzopa z1fc 144hz portable gaming monitor.

Gamers should consider this monitor, which boosts the refresh rate to 144Hz. You’ll get an extra-responsive monitor with the same benefits the Z1RC offers. Best of all, this monitor is even cheaper, at $99.99. The Z1FC offers 100% sRGB gamut and 1080P FHD resolution to provide a crisp, vivid display. For other options from the same brand, check out an Arzopa A1 Portable Monitor review or an Arzopa Z1FC 144Hz Portable Gaming Monitor review .

ASUS ZenScreen Touch MB16AMT

One downside of the Z1RC monitor is that it doesn’t feature touchscreen technology. ASUS’s ZenScreen Touch MB16AMT has a highly responsive touchscreen that works best with Windows devices. It also has a built-in battery that offers up to four hours of use on a charge, so you won’t have to worry about draining your laptop battery. At $379, though, it’s a bigger investment than the Arzopa Z1FC.

Sidetrak Solo Pro FHD 15.8-inch

At $229.99, this monitor from Sidetrak isn’t quite as expensive as the ASUS, but it’s more expensive than the Arzopa Z1RC. It also brings a 60Hz refresh rate and vivid graphics. The stand is more substantial, although you can’t adjust the angles as you can with the Z1RC. This monitor is also slightly heavier, at 1.81 pounds, and it lacks the durability you get from Arzopa’s monitors.

The AP Buyline takeaway:

This lightweight monitor makes working on the road easy, with a high-definition display that’s great for work documents, light video streaming and casual gaming.

Frequently asked questions (FAQs)

How do you connect an arzopa monitor to a laptop.

Unlike other peripheral devices, portable monitors typically connect via a cable rather than Bluetooth. That’s why it’s essential to check the ports on your devices before buying a monitor.

“Most modern laptops either have an HDMI or USB-C port,” says Sam Devia of eRepair , a device repair shop in Chicago. “If it has an HDMI port, you’ll be able to use a standard HDMI cable. If it has USB-C, you can use a USB-C to USB-C connection if the portable monitor also has one.”

How do you power an Arzopa monitor?

Like many portable monitors, the Arzopa monitor gets its power from the connected device. Steven Athwal, CEO and founder of The Big Phone Store , steers clear of those that don’t. “I recommend avoiding those that use A/C power adapters,” he says. “In addition to these being bulky, having a built-in battery or USB power allows for flexibility and on-the-go use.”

Can you connect an Arzopa to a phone?

Arzopa monitors can connect to a variety of devices, including phones. You’ll need to check compatibility and make sure you have the right cables for the job.

“For connecting a portable monitor to a phone, you will need an adapter and an HDMI cable,” says Amruth Laxman, founding partner at 4Voice . “Connect the adapter to the USB port on your phone and then connect the HDMI cable to the adapter. The other end of the cable goes into the port on your monitor. Typically, your monitor will detect the device and walk you through the setup. You can also open the HDMI source on your monitor to connect with your phone screen.”

Does Arzopa have Bluetooth?

The Arzopa Z1RC monitor doesn’t have Bluetooth built in. It relies solely on cables to connect to devices.

• Open access
• Published: 29 July 2024

Magnitude and outcome of road traffic accidents among patients admitted in dessie town governmental hospitals, Northeast Amhara, Ethiopia, 2022

• Fatuma Seid Degu 1 ,
• Adem Hussein Endris 1 ,
• Samuel Anteneh Ayele 1 ,
• Natnaiel Grima Melkie 1 ,
• Mitaw Girma Kenbaw 1 ,
• Mekuriaw Wuhib Shumye 1 ,
• Missale Kassahun Hirpo 1 ,
• Atrsaw Dessie Liyew 2 ,
• Mandefro Assefaw Geremew 2 &
• Prem Kumar 1  

BMC Emergency Medicine volume  24 , Article number:  138 ( 2024 ) Cite this article

129 Accesses

Metrics details

Road traffic accidents(RTA) are a major public health problem worldwide, accounting for almost 1.24 million deaths per year and it is the number one cause of death among those aged group 15–29 years. Even though there are great benefits from access to road transportation there also poses a great challenge in the individual’s daily activities ranging from minor injury to death.

This study aimed to assess the magnitude and outcome of road traffic accidents among patients admitted in Dessie Town Governmental Hospitals, Northeast Amhara, Ethiopia, 2022.

A five-year hospital-based retrospective descriptive cross-sectional study design was conducted among 377 road traffic accident patients admitted to Dessie Town Governmental hospitals. Data were collected by simple random methods based on patient chart reviews from June 7/, 2022 to May 23/ 2017 using a checklist adapted from the WHO standard hospital-based road traffic accident questionnaires after obtaining consent from the concerned authority. EPI-Data software version 7.2 for data entry and SPSS version 25 for statistical analysis were used. Descriptive and inferential statistics were used. Statistical significance was declared at a p-value of < 0.05 with an adjusted odds ratio (AOR) and a 95% confidence interval (CI) in the final multinomial logistic regression model.

The magnitude of road traffic accidents was 59%, using of logistic multi nominal logistic regression we found results such that, road traffic victims who had unstable vital signs at admission (AOR = 6.4,95% CI; 2.5–16.6), didn’t get prehospital treatment (AOR = 9.3,95% CI; 4–20), and severe injury (AOR = 9, 95% CI;7-15.4), had a Glasgow coma scale of 3–5 (AOR = 5.2,95% CI; 1.4–20) were found predictors for death were as unstable vital signs at admission (AOR = 3.79,95%CI;2.1–6.8), Doesn’t get prehospital treatment (AOR = 2.8, 95% CI; 1.4–5.7), Hospital stay for one to two months duration (AOR = 6,95% CI;2.3–15), and greater than two months duration (AOR = 6.5,95%CI;2.5–17) were found predictors for disability among road traffic victims.

Conclusions and recommendations

Road traffic accidents constitute a major public health problem in our setting and contribute significantly to excessively high morbidity and mortality. Unstable vital signs at admission, Client doesn’t get prehospital treatment, severely injured client, and had a Glasgow coma scale of 3–5 were found predictors for death were as an unstable vital sign at admission, Client doesn’t get pre-hospital treatment, Hospital stays for one to two months duration, and greater than two months duration were found predictors for disability among road traffic victims.

Peer Review reports

Introduction

Road transportation has a direct connection with the day-to-day activities of people, especially in large cities where the distance to be traveled is too far to cover on foot or by bicycle within a reasonable time. The Global Status Report on Road Safety 2023 shows that the number of annual road traffic deaths has fallen slightly to 1.19 million [ 1 ].

According to the report on road traffic injury showed that the number of road traffic injuries has continued to rise in the whole world, but there has been an overall downward trend in road traffic deaths in high-income countries since the 1970s and an increase in many of the low-income and middle - income countries. Deaths related to road traffic injury (RTI) are predicted to increase by 83% in low-income and middle-income countries and to decrease by 27% in high-income countries [ 2 ]. The severity of road traffic accidents is also likely to be much greater in Africa than anywhere else because many vulnerable road users are involved, poor transport conditions such as lack of seat belts, overcrowding, and hazardous vehicle environments. The poor reporting system has also masked the magnitude of the problem in the Africa region. The lack of pre-hospital and hospital emergency care after accidents makes the outcome of car accidents the worst in Africa. African countries had the highest mortality rate, with 28.3 deaths per 100,000 populations, and, In Ethiopia a road traffic fatality rate of 37 per 100,000 population [ 3 , 29 ]. Ethiopian Federal Police Commission recorded 15,034 road accidents in 2021, resulting in 4,161 deaths, surpassing the World Health Organization’s 2013 record of 4,984.3 deaths per 100,000 vehicles per year[ 4 ]. Over the 45 months from September 2013 to May 2017, 3385 road traffic accidents were reported in Amhara Region. The average monthly number of accidents was 76, with the highest being 108 and the lowest being 43 [ 28 ]. Dessie Town took the third rank, following Gondar and Bahir Dar city 86.3%,54.8%, and 48.5% respectively [ 5 ].

Scholars suggest factors contributing to fatality rates in road traffic victims include age (> 60 years), systolic blood pressure, Glasgow coma scale, head injury, time to reach a health facility, patient condition, hospital days, abdominal injury, transfer status, blood transfusion, ICU admission [ 6 , 7 , 8 , 9 ]. Delay to come to the hospital (over 24 h), the severity of injuries, and management types [ 10 ] were significant indicators of death among the road traffic victims. According to many studies notify that, Road traffic accidents affect not only the health of individuals but also their family members, as it can drive households into poverty when they struggle to cope with the long-term consequences of the events, such as the costs of medical care, rehabilitation and loss of family’s breadwinners. RTAs have substantial adverse effects on national health systems as well, many of which already have suffered from woefully inadequate levels of resources [ 11 ]. Rescue the trapped casualties, looking for breathing, heart function, and consciousness, controlling bleeding and fractures, and moving the casualty to the closest hospital were considerable treatment measures [ 12 ] (Figure 1 ).

Conceptual framework shows the relationship between dependent and independent variables

Currently, there is limited literature to generalize the country’s context. However, no study has addressed the trends of road traffic accidents for at least five years of duration. Adding to this, similarly, previous researchers used logistic regression only, whereas the current study used multinominal logistic regression and included the new variable disability and outcome variables, and this study insight into hospital administrative units’ national road safety commissions, motor traffic, and transport units, and other stakeholders to develop effective treatment responses and strategies for road accident admission victims. It also provides evidence on effective road traffic accident prevention, patient care, and rehabilitation, serving as a baseline for future research. Hence the study aimed to assess the magnitude outcome of road traffic accidents among patients admitted to Dessie town governmental hospitals.

Method and materials

Study design, area, and period.

The hospital-based retrospective descriptive cross-sectional study design was conducted at Dessie Town governmental hospitals; Dessie Town is one of the eleven zones in Amhara Regional state and the city of the South Wollo Zone. It is located at a distance of 401 km from Addis Ababa. According to the 2007 Central Statistical Agency report, Dessie has 285,530 populations in 2021/2022, of which 49.5% are men. In 2019/2020, there were 8 health centers, 8 health posts, 2 government hospitals, 3 private hospitals, 38 private clinics, 55 private drug stores, and 4 private diagnostic laboratories. Dessie Town governmental hospitals as the three main wards in the hospital, the orthopedic, medical, and surgical wards, together treat about 3600 patients annually. There are currently 39 beds in the surgical ward with five general surgeons and 19 staff members and 36 beds in the orthopedic ward with two orthopedics and 12 staff members providing care [ 13 ]. Boru Media General Hospital is located 20 km from Dessie Town and has different departments and wards surgical wards have 10 beds and the orthopedic has 7 beds with 3 surgeons and 12 staff was currently giving services. Moreover 409 road traffic patients were visited per month in the respective study area. The study was conducted from June 7/2022-23/ 2022.

Source populations

All patients who experience RTA traumatic injury are admitted to Dessie Town governmental hospitals.

Study population

All patients admitted with road traffic accidents to Dessie Town governmental Hospitals during study periods.

Sample size and sampling method

Sample size determination using a single population formula

P = proportion = 33.6% (14).

\(\:\left(\mathbf{Z}\frac{\varvec{\alpha\:}}{2}\right)2\) =1.96

D = Degree of precession = 5%.

By adding a 10% non-response rate the final sample size was 377 (Figure 2 ).

Sampling technique: A simple random sampling technique was used to select study participants.

Sampling procedure about the of road traffic accident, and treatment outcome at Dessie Town governmental Hospitals, North east Ethiopia, 2022

Variables of the study

Dependent variables: Magnitude of Road Traffic Accidents.

Independent variables.

Socio-demographic characteristics

Age, Sex, Educational status, marital status, Residence, and occupation.

Environmental and clinical related factors

The factors such as Type of injury and Hospital, Length of hospital stay, body area/part involved degree of injury as mild, moderate and severe, vital signs at admission, management type, Glasgow coma scale at admission, and comorbidity disease.

Data collection tools and procedures

Data was collected using a checklist adopted from the WHO hospital-based standard with 15 main questionnaires of road traffic accidents by 3 BSc nurses and one supervisor after they were trained by the principal investigator for one working day before the actual data collection date. To get the patient’s primary files from the card room, the card number was first taken from the log books in each department, including the emergency room, operating room, surgical, and medical inpatient records. To gather the necessary information for the study participants, the patient’s card’s medical record number (MRN) was fully listed next to it, along with the relevant study periods. Then all MRNs were cross-checked across each department and unit to avoid any duplication. Finally, based on the inclusion criteria of the study cards which had all variables for the study were selected based on simple random techniques after a proportional allocation number of cases per year. Then all variables like pre-hospital care, body part injured, types of diagnosis, treatment modality, treatment outcome, and other variables were collected from chief complaint, history of present illness, progress, admission, and discharge note.

Data processing and analysis

The data was entered by Epidata Version 7.2 and analyzed using SPSS version 25. Data cleaning was performed to check for frequencies, accuracy, consistency and missed values and variables. Any error identified during data entry was corrected after revision of the original completed checklist.

Statistical significance was declared at a p-value of < 0.05 with an adjusted odds ratio (AOR). To explain the study population about relevant variables descriptive like percentage, and frequency, and analytical statistics like, tables, and binary and multivariate logistic regression were used to present data and to show the relationship between the dependent and independent variables in the study. All explanatory variables enter into the multivariate logistic regression model to control the possible effect of confounders and by using the backward stepwise regression method. Finally, the variables had an independent association with treatment outcome, death, and disability was declared based on 95% CI and p-value < 0.05. Model fitness was checked by using the Hosmer and Lemeshow’s goodness of fit test which was 0.954.

Data quality control and assurance

A pre-test was done with 5% of the sample size at Kemissie General Hospital, Ethiopia. The data collectors and supervisor were trained for 2 days on how to collect the data from the particular participants. The progress of data collection was scrutinized by the supervisor every other day. Model fitness was confirmed by the Hosmer and Lemeshow test, and it was 0.954.

Operational definition

Physical damage to the body, intentionally or unintentionally [ 15 ].

Degree of injury

The degree of the injury is determined by the extent of the injury, including superficial, moderate, and severe injuries, which require skilled treatment [ 14 ].

collisions involving two or more automobiles with automobiles as well as automobiles with people, automobiles with animals, and, automobiles with immovable or fixed objects [ 15 ].

Any patient or victim admitted and starting treatment at selected healthcare facilities [ 29 ].

It is the implementation of measures of the immediate care taken of the lives of people with traumas and illnesses until they are given professional medical assistance [ 30 ].

Good treatment outcome

The client remained discharged with improvements and/or deprived of impediments like hearing loss, vision loss, amputations, and so on. [ 15 ]

Poor treatment outcome

If the patient remained discharged through complications or transferred/shifted to a tertiary or specialized health setup, or deceased in the hospital [ 15 ].

Death at arrival

It refers to the death of a patient when brought to the hospital and /or within an hour of existence at the hospital [ 15 ].

Individuals who travel in a vehicle or transport system [ 31 ].

A person transporting themselves in the most natural expression of what it means to be human [ 32 ].

Socio-demographic characteristics of the study participants

A total of 377 participants were enrolled in this study, making a 100% response rate.

The mean ages of the study participants were 27.34 years with (SD, 12.86). More than half of the study participants, 237 (62.9%) were male. Regarding their marital status, 129 (34.2%) were married. Concerning their religion, 244 (64.7%) were Muslim, Protestant 54 (14.3%), and 79(21%) were Orthodox. Regarding their educational status, more than one-fourth of the study participants 167 (44.3%) were attending primary school followed by 74 (19.6%) unable to read and write. Concerning their residency and working status, nearly two-thirds of the study participants 236 (62.6%) were urban dwellers and 128 (34%) were students followed by 85 (22.54%), housewife 53 (14.1%), civil servants, and 49 (13%) were traders (Table 1 ).

Nature of the injury, diagnosis, their location, and Hospital name

The finding of this study showed that, all most three fourth of victims 281 (74.5%) were attended at Dessie Comprehensive Specialized Hospital followed by Boru Media General Hospital 96 (25.5%). Concerning the place where the victims came to hospitals 159 (42.2%) of the victim came from health centers followed by 131 (34.7%) from primary Hospitals, and 87 (23.1%) from the scene. Regarding of region of injury, musculoskeletal (lower extremities) 80 (21.2%) were the most affected region of the body followed by the Chest 80 (18.6%), head and neck 67 (17.8%), abdomen 51 (13.5%), upper extremities 38 (10.1%), bone fracture 33 (8.75%), and more than one parts of the body 28 (7.4) were accounting of the cases. Concerning the diagnosis of cases, internal organ injuries 108 (28.6%) was the most diagnosed injury followed by fracture and dislocation 96 (25.5%), head injury 51 (13.5%), soft tissue injury (Bruise, abrasion, laceration) 50 (13.3%), multiple organ injuries 49 (13%), and 23 (6.1%) were spinal cord injury (Table 2 ).

Vehicle type that was involved in the accident and patient condition related to road traffic accidents

This study showed that 111 (29.4%) injuries were caused by Bajaj followed by, 91 (24.1%) by Motor cycle, 61 (16.2%) by Taxi, 44 (11.7%) by a heavy trucks, 28(7.4%) by Pickup, and the remained caused by Bus, Minibus, and other vehicles. Concerning the admission ward, nearly half of the road traffic victims 180 (47.7%) were admitted to the surgical ward followed by 106 (28.1%) in the ICU ward, 71 (18.8%) in the paediatric ward, and 20 (5.3%) were admitted in the medical ward. Concerning Hospital treatment more than half percent of the victims 217 (57.6%) were gate pre Hospital treatment and stable Vital sign were saw among 222 (58.9%) road traffic victims during admission more than 158 (41.9%) of the road traffic victim were severely injured followed by 139 (36.9%) Moderately injured, and 80 (21 0.2%) were had minor injury related road traffic accidents. Concerning the mental status of the victim 160 (42.4%) had a GCS range of 3–8 followed by 141 (37.4%), a GCS range of 9–12, and 76 (20.2%) with a GCS range of 13–15. Regarding comorbidity disease 120 (31.8%) victims had comorbidity diseases. Regarding hospital length of stay, 168 (44.6%) stayed at the hospital for less than one-month duration followed by 104 (27.6%) were stayed for one to two months duration, 70 (18.6%) stayed for three to months duration, and 35 (9.3%) stays for more than three months duration in the hospital this including the day spent for follow up after they were discharged (Table: 3 ).

Magnitudes related to road traffic accidents

In this study, 377 road victims participated at Dessie Town governmental Hospitals with the magnitude of road traffic accidents found to be 59% throughout 5 years at DessieTown governmental Hospitals showed that the road traffic accidents dramatically increased from the year 2010 until the year 2014 according to Ethiopian calendar (figure 3 ).

Road traffic accident trends in the 5 years at Dessie Town governmental hospitals from June 7/2022 to May 2017 Northeast,2022 ( n  = 377)

Factors associated with death

To assess the association of different independent variables with treatment outcome, bivariable multinomial logistic regression analysis was conducted for a crude association, and all variables with a (P-Value  ≤  0.2) were candidates for multivariable multinomial logistic regression. unstable vital sign at admission (AOR = 6.4,95%CI; 2.5–16.6), unable to gate prehospital treatment (AOR = 9.3,95% CI; 4–20), and severee injury (AOR = 9, 95% CI;7-15.4), and had Glasgow coma scale 3–5 (AOR = 5.2,95%CI; 1.4–20) were found predictors for death among road traffic admission victims.

Factors associated with disabilities related to road traffic accident victims

The findings of this study shows that unstable vital signs at admission (AOR = 3.79, 95%CI;2.1–6.8,), Do not getting Hospital treatment (AOR = 2.8, 95% CI; 1.4–5.7), Hospital stay for one to two months duration (AOR = 6,95% CI;2.3–15), greater than two months duration (AOR = 6.5,95%CI;2.5–17) were found predictors for disability among road traffic accident admission Victims (Table 4 ).

This study revealed that the prevalence of road traffic accidents was found to be 59%.

This result is in line with the study carried out in Yirgalem General Hospital, Southern Ethiopia with the prevalence reported as (51.4%) [ 16 ]. in Wolaita Zone, SNNPR, Ethiopia where the prevalence was 62.5% [ 17 ], in Adama Hospital Medical College, Central Ethiopia where the prevalence was reported as 54.7% [ 10 ].

On the other, the present study finding was higher than the studies done in the emergency departments of the University of Gondar Comprehensive Teaching and Referral Hospital (UOGCTRH) which was found as 33.6% with (95%CI: 28%, 39.1%) [ 14 ]. In the Emergency Department at Tikur Anbessa Specialized Referral Hospital, Addis Ababa, Ethiopia the prevalence was reported as (38.3%) [ 18 ].

The variation of the prevalence for the UOGCTRH study might be due to the study period which was only for 6 months duration and it was limited to the specific departments which was done in the emergency department only and the prevalence variation for Tikur Anbessa Specialized Referral Hospital was the first thing was the duration of the study done for only three months duration and also it was area specific which were done in the emergency department.

On the contrary, the prevalence of road traffic accidents was lower than in the study done in the Emergency Department of Tikur Anbessa Specialized Teaching Hospital, Addis Ababa, Ethiopia where the prevalence was reported as 74% [ 19 ]. The variation of the prevalence for this study might be due to the study area where conducted in Addis Ababa Ethiopia, the most transportation-covered area since the town is the capital city of Ethiopia. The study was conducted in Saudi Arabia (84.4%) [ 20 ], in Vellore district, southern India (73%) [ 21 ], and, in Diredawa, Eastern Ethiopia (80%) [ 22 ].

Regarding associated factors, road traffic accident victims who have unstable vital signs at admission are six times more likely to die as compared to clients who have stable vital signs (AOR = 6.4, 95%CI; 2.5–16.6). Associated between unstable vital signs and death among traumatic patients was reported in a study done at the Adult Emergency Department of Tikur Anbessa specialized hospital, Addis Ababa, Ethiopia which states that systolic blood pressure which is one of the vital signs was a statistically significant predictor of fatalities among the road traffic victims [ 7 ]. Moreover clients unable to gate pre Hospital treatment have nine times more likely to die as compared to client gate pre Hospital treatment (AOR = 9.3,95% CI; 4–20). This finding was supported by the study done by Bugando Medical Centre in Northwestern Tanzania [ 23 ]. Which states that prehospital care is a very important factor in determining the outcome after injury [ 24 ]. In the current study clients who have severe injury were nine times more likely to die as compared to clients who have minor and moderate injury (AOR = 9, 95% CI;7-15.4). The finding of the study was supported by a study done at a Tertiary Hospital in Kenya [ 6 ]. and at Bugando Medical Centre in Northwestern Tanzania as reported as a High mortality rate was recorded in patients with severe trauma at admission [ 22 ]. Finally, road traffic victims having a Glasgow coma scale of 3–8 were five times more likely to die as compared to road traffic victims having a Glasgow coma scale of 9–12 and 13–15 (AOR = 5.2,95% CI; 1.4–20). This result was supported by a study done in Jimma Ethiopia [ 8 ]. This states that patients with low GCS are highly liable for a bad outcome that could be due to major organ failure, especially severe head injury.

Regarding factors associated with disabilities related to road traffic accident victims.

The current study discovered that unstable vital signs at admission (AOR = 3.79, 95% CI; 2.1–6.8) was nearly 4 times more likely to develop a physical disability, this study results in line with the study done in Dar es Salaam, Tanzania [ 25 ]. The other concern related to road traffic victims who Don’t get pre-Hospital treatment were nearly three times more likely to develop functional disability as compared to road traffic victims who got pre-hospital treatment (AOR = 2.8, 95% CI; 1.4–5.7) this finding was supported by the study done in Tikur Anbessa specialized hospital, emergency department [ 26 ]. as stated as It is obvious that primary prevention is the best way to avoid or to reduce rates of death or disability from a life-threatening injury. Moreover, Hospital stay for one to two months duration (AOR = 6,95% CI; 2.3–15) and greater than two months duration (AOR = 6.5,95% CI; 2.5–17) were nearly seven times more likely to develop physical disability as compared to clients who stay in hospital Less than one-month duration among road traffic accident Victims this founding was supported by a study done in China as state that performance of daily activities were associated with prolonged hospital stay [ 27 ].

Since the current study was cross-sectional, this is weak to evaluate the cause–effect relationship also the current study depending to the client’s chart review some important information like the victim’s time spent before rich to the hospital and substance use was difficult to access.

The findings of this study showed that the magnitude of road traffic accidents was found to be 59%. Unstable vital signs at admission, Don’t getting pre-Hospital treatment, Hospital stay for one to two months duration, and greater than two months duration were associated.

Recommendation

The health care providers working in the respective ward and unit care service better give strong attention to road traffic victims those having unstable vital signs at admission, unable to get pre Hospital treatment, sever injury, and victims having a Glasgow coma scale of 3–8, and Hospital stay for more than one month duration. Better treatment outcome including disabilities free road traffic victims.

It is better incorporated in routine follow up on community awareness program on rood traffic safety. To assess Magnitude and outcome of Road traffic accident among Patients Admitted to Dessie town Governmental Hospitals, are better evaluated in prospective study design.

Data availability

The datasets used and/or analyzed during the current study are available from the Corresponding author upon reasonable request.

Abbreviations

Adjusted Odds Ratio

Bachelor of Sciences

Confidence Interval

Glasgow Coma Scale

Road Traffic Accident

Road Traffic Injuries

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Acknowledgements

First I would like to extend my sincere thanks to the Wollo University College of Medicine and Health Sciences community and research office for creating a good opportunity. Next to this, I give Special thanks to Dessie Town a governmental hospital administrates, card room staffs, and health informatics staffs for providing all the necessary data to do this thesis. Finally I greatly thank my friends for their constructive comments.

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Fatuma Seid Degu, Adem Hussein Endris, Samuel Anteneh Ayele, Natnaiel Grima Melkie, Mitaw Girma Kenbaw, Mekuriaw Wuhib Shumye, Missale Kassahun Hirpo & Prem Kumar

Department of Midwifery, College of Medicine and Health Sciences, Wollo University, Wollo, Ethiopia

Atrsaw Dessie Liyew & Mandefro Assefaw Geremew

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FSD, wrote the study, analysis, interpretation and final approval to final version to published AHE, SAA, NGM, were made figures MGK, MWS, and MKH, were wrote tables, and ADL, MAG and Dr. PK participated in data collection.

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Correspondence to Fatuma Seid Degu .

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The study was approved by the Research Ethical Review Committee (IRERC) of the School of Nursing, College of Medicine and Health Sciences. Permission was obtained from concerned authorities of the Dessie Town governmental hospitals. Participation was completely voluntary and informed written consent was obtained from all hospital administrative. The study subjects after in-depth clarification about the objective of the study. All information obtained throughout the study was kept confidential. This study was conducted as per the Declaration of Helsinki.

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The study does not include images or videos relating to an individual. But concerning collected and used data in this study was using a medical card number by avoiding using their names while obtaining consent from each hospital administrative, information related to publishing the study findings was addressed, and the administrative agreed on that.

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Degu, F.S., Endris, A.H., Ayele, S.A. et al. Magnitude and outcome of road traffic accidents among patients admitted in dessie town governmental hospitals, Northeast Amhara, Ethiopia, 2022. BMC Emerg Med 24 , 138 (2024). https://doi.org/10.1186/s12873-024-01047-1

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Received : 25 January 2024

Accepted : 10 July 2024

Published : 29 July 2024

DOI : https://doi.org/10.1186/s12873-024-01047-1

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