Risk Assessment of the main transport corridor in Iraq

The increased rate of road fatalities ad injured has been a vital issue. Risk assessment of road project is essential in the planning and design stages to prevent road crashes occurring in the operational stage. In Iraq, the main transport corridor has been designed to connect major cities and used by significant traffic volume which led to increase in the crash fatalities. Therefore, it is important to identify the risk factors and improve the safety level. This paper aims to assess the risk of part of the main transport corridor in Iraq. The selected section is part of Road 9 which connects Abu Gharib district with Fallujah City. The selected methodology of assessment is based on the road features and supported traffic data developed by the International Road Assessment Program (iRAP) agency. The output of the assessment is in terms of star rating and star rating score. Higher star rating means safer road condition while higher star rating score means more dangerous road condition. The results of assessment show high level of risk for vehicles. A set of road improvements that meet safety standards are proposed such as improving delineation, lighting, Metal barriers for the median, central strips, intersection channelization, Various repairs according to the severity of the damage at pavement and using shoulder rumble strips. The results of assessment after improvements show upgrading the star rating to the recommended minimum (3 and 4 stars) for vehicles.


Introduction
Annually, and 20 to 50 million people suffer non-fatal injuries due to traffic accidents.Increasing the rate road fatalities is highly connected with issues related to the sustainable development because of its negative social and economic consequences; people and countries have facing social issues and economic losses for treatment costs or loss of productivity; the cost of traffic accidents is 3% of Gross domestic product [1].Road network and transportation system have been becoming more dangers for road user sand road properties [2].The risk level of road infrastructures is substantially impacted by several factors such as road user behavior and road geometric features [3][4][5][6].Therefore, it is essential to consider these factors in road safety studies and in the design of road network to reduce the risk level and prevent live loss in roads.Therefore, global agencies have recognized this important issue and have efforts to control the global increase in the rate of fatalities which reach 1.3 million people annually [1].The United Nations have declared that the decades (2011-2020) and (2021-2030) are the decade of road safety actions.Due to the role of road safety issue sustainable development, the target of reducing the rate of road fatalities to the half by 2030 is included as target (3.6) in the agenda of sustainable development goals (SDG) that was published in 2011.Safer road network is also included as target (11.2) in the SDG which is related to the targets of safer and more sustainable cities [7][8].
IOP Publishing doi:10.1088/1755-1315/1232/1/012056 2 Iraq has the second-highest accident rate among Middle Eastern nations.ashigh rate of accident are reported [9].Therefore, improvements have been implemented in some major roads to reduce the size of issue.In addition, several researches have been conducted to study the road safety issue in Iraq and consider the various factors.Al-Dulemi [10] found that the lane marking has significant effect on the road safety level of rural road in Iraq while Jrew et al. [11] found that road length, lane width, number of lanes, traffic density, and number of speed calming, number of pedestrian bridges and crosswalks, and the availability of median have higher impact in road network in Erbil city.Aldoski et al [12] focused more in his research on surface and addressed its significant effect on the road risk level while Diah et al. [13] and Albayati and Lateif [14] highlighted the impact of road functional classification and the lighting in increasing the road accidents.
Jameel and Al-Nuaim [15] used iRAP [16], the most recent methodology in quantifying the risk level of the old Baquba-Baghdad rural road which is a two way-two lane road.They found that number of lanes; using separating physical and improving the skid resistances of the road surface have contributed in reducing the fatalities rate by about 60%.Jameel et al. [17] used iRAP also to assess the likelihood and severity of the same road according to the crash types.They found that road surface rehabilitation is important to avoid the likelihood of run-off and head-on crashes while improvement of the roadside characteristics and removing the huge objects led to reduce the severity level of run-off crashes.They found also that upgrading the median type has the significant role in reducing the severity level of head-on crashes.The iRAP evaluation score, which is expressed as a star rating, is included as a measurable global aim to achieve the Sustainable Development Goal (SDG) and the Decade of Actions on Road Safety (DARS) targets, three stars is the minimum to save the lives of 50% of drivers.The iRAP is used widely over the globe.
With increasing the road projects in Iraq, it is necessary to increase the road safety assessment project in order to avoid more dangerous road and saving life in roads.Therefore, this paper aims to assess the risk level of a planned road rehabilitation project based on geometric feature.To achieve this aim, steps are explained in the next section.

Methodology
Figure 1 shows the steps followed in this research which is explained in the further sections.

Selecting the study area
The selected study area is part of Expressway 1 Road No. 9 (R9) which connects Baghdad City and Hit City [18], which is a part of the western section of Iraq's main transport corridors [19].It is considered one of the most important roads in the trade exchange between the western borders in Iraq and the rest of its regions.The selected section for this study connects Abu Ghraib district with Al-Fallujah City with length of about 30 km, as shown in Figure 2 [19].It consists of three lanes for each side divided by physical concrete median in some areas and by metal safety barrier in other areas.The rehabilitation project of the main transport corridor in Iraq has been funded by the World Bank to enhance its performance after recuperating from years of wars and violence.

Collecting the road attributes and traffic data
The main data needed as input variables for assessing the risk level are classified into road attributes and traffic data.
Road attributes were collected from the site observation and plans documented by the Ministry of Construction and Housing / Roads and Bridges Authority.These data include the variables that affect each type of accident for each road user group identified through literature review such as, land use, area type, median type, roadside object, shoulder rumble strips, paved shoulder, number of lanes, lane width, curvature, quality of curve, grade, road condition, skid resistance / grip, delineation, and street lighting.These data are attributed according to the categories of iRAP methodology [20].For example, when there is no roadside object, the attribute is "no object" and the distance to the nearest object is categorized to less than 1m, 1-5m, 5-10m and greater than 10m.The attributed road data is shown in Table 1.
Traffic data includes the average annual daily traffic (AADT) which was collected from project documents.The AADT was 9554 vehicles per day along the road section.The traffic flow of motorcyclists, bicyclists and pedestrians should also be collected; the flow was recorded as zero as there has been not observed flow for these road user groups.

Quantifying the risk
The methodology and risk assessment programs have been examined in order to choose the most suitable program for quantifying the risk of the chosen road [20,21].The International Road Assessment Program (iRAP) has been selected for several reasons [22][23][24][25].It is utilized globally and used as the official standard in about 100 nations.In addition, it can be used for both road risk assessment and treatment program.Furthermore, since it is based on the characteristics of road infrastructures, historical data is not needed.Moreover, the program has been verified and the specialists in road safety recommend it.Additionally, the World Bank advises evaluating the risk of new and existing road networks.It is also free online accessed.VIDA, which is an online road safety assessment and star rating analysis tool produced by iRAP is used to get the star rating.

Coding data
In accordance with the iRAP methodological codes, the data were coded.For example, the code of the safety metal barrier is 1 while the code is 4 when there is no object [19].The results of coding are shown in Table 1.

Processing data
To find the assessment findings, the codes were entered into the iRAP application.The outcomes are expressed as star rating score and star ratings [19].The star rating score (SRS) is resulted for four crash types which are run-off (for both sides), head-on due to loss of control (LOC), head-on due to overtaking and intersections crashes; the overall SRS is also produced.The star rating (SR) is also produced; five-stars represent the highest safe level while one-star rating represents the lowest-safe level.When the SRS is between 12.5 and 22.5, the SR is 2; when it is less than 12.5, the star rating 1s 3 [19].The results of SR are shown in Table 2.

Analyzing results
The results of the SR show the high-risk level of the assessed road section which reflecting the lack of safety requirements standards in the design of the road.Therefore, improvements in the road feature design are required to upgrade the SR to minimum 3 stars as recommended by the iRAP agency [19].
For this, the risk factors road features should be identified.According to the SRS results shown in Table 2, the highest SRS was estimated for run-off road crashes; especially from the passenger side for all segments.The head-on crash has high crash score also for some segments.The head-on overtaking crash has zero SRS which means that the road feature of the assessed road section meets the standards that prevent the likelihood of this crash type.The intersection crash has zero because they are not taken into accounts in this study.
The road attribute risk factors for run-off crashes and head-on crashes should be identified to propose the suitable countermeasure.According to the road attribute risk factors identified by iRAP [19], the influenced road attributes are roadside hazard, paved shoulder, road conditions, delineations, street lighting, skid resistance, centerline and shoulder rumble strips, median type, curvature and quality of curves, and grade.According to the existence conditions of the assessed road section, the marked sections where there are high risk factor road attributes are shown in Table 3.It can be seen that the road side hazard object is existence in segments 22.3 to 26.4, 26.6 to 28.3, and 28.7 to 30.0 where the distance to the median safety barrier on the driver side should be wider.These segments are highlighted as having high risk for crashes because of the existence of safety barrier.Poor and medium road conditions and skid resistance, and the lack of street lighting are observed in some segment.Poor delineation, lack of shoulder and rumble strips and lack of speed management reviewing are recorded along the road section.
The results of this analysis will be used in the next step to propose the suitable set of countermeasures.

Improvement of the safety level
Several suggestions have been proposed based on the identified high-risk road attributes to obtain a road with a higher safety rating.The suggestions are improving delineations, installing safety barriers with distance greater than 10m, installing lighting where they are missing, resurfacing with highquality asphalt mixture to improve skid resistance and road conditions, installing centerline and shoulder rumble strips.

The proposed countermeasures
• Improvement of the delineation Improving delineations is considered one of the most economical countermeasures to improve the road safety level.Drivers can better understand their position on the road and receive information about impending conditions by using effective delineations.Delineation techniques are especially useful on sharp bends and in situations when visibility may become poor (for instance, due to rain, fog, or darkness).Delineation techniques come in a variety of forms such as Line marking; Retro Reflective Pavement Markers (RRPMs), and Chevron Alignment Markers (CAMs), guide, warning signs, and advisory speed signs are a few examples of demarcation treatments [26].
• Using rumble strips and centerline rumble strips Rumble strips have been used on roadways as a warning device for many years by traffic and road specialists' shoulders.The purpose of shoulder rumble strips is to warn drivers when they are about to leave or have left the travelled road and when a steering adjustment is necessary to get back on it.
On an undivided road, centerline rumble strips are placed between opposing lanes of traffic to warn drivers that they have crossed into the path of oncoming traffic.These strips are modeled after shoulder rumble strips, which warn drivers when they are leaving the traveled roadway.This alert manifests as an increase in interior noise and a vibration of the car resembling shoulder rumble strips.The New Jersey Turnpike Authority conducted a before-and-after analysis of right-shoulder collisions.Rumble strips revealed a 34.3% decrease in run-off-the-road collisions following their implementation.Shoulder rumble strips while mainline collisions on the whole increased by 11.4% [27].
• Using safety barrier When there are very few motorized two-wheel vehicles on the road, road safety barriers are crucial in Reducing.The Affects of RTA [28].Barrier systems that are placed in accordance with the essential regulations According to a safety performance audit in China, increase traffic safety level [29].
• Improvement of Lighting Numerous significant advantages are offered by street lighting.By artificially prolonging the hours of daylight so that activity can occur, it can be utilized to improve security in metropolitan areas and the quality of life.Additionally, street lighting increases pedestrian, cyclist, and vehicle safety.Driving at night is riskier; about 40% of fatalities and serious injuries occur at night [30].
• Improvement of skid resistance Many crashes might have significant contributing causes including skidding and loss of control.In areas where braking is frequently employed, such as on approaches to crossroads, at pedestrian crossings, and at curves, special attention should be paid to the roadway surface's sliding resistance characteristics.If there is a buildup of oil or other debris on the road, there is inadequate road drainage, or the road surface becomes worn (aggregate becomes polished) from driving, poor skid resistance may eventually emerge.The two most common solutions for treating low skid resistance are resurfacing and retexturing.Retexturing is the process of mechanically altering an existing surface to improve its frictional characteristics and, consequently, its resistance to slipping.This is involving typically cleaning the road's surface of debris.Some of the methods include diamond grooving, shot blasting, bush pounding, and high velocity water blasting.Resurfacing involves applying thin, very inexpensive surfacing treatments that can increase the smoothness and resistance to wet road skidding [26], seal the surface against water penetration, and stop the current road surface from deteriorating .
• Improving road conditions Distresses in the pavement have a direct impact on ride quality and indirectly affect accidents, driver distraction, and vehicle performance.For instance, a vehicle may lose control when braking or turning on a road with a history of roughness or potholes, especially in poor weather conditions.Lower brake friction is caused by a reduction in tire-to-pavement contact area when pavement roughness rises.Additionally, because there may be varying friction forces on the two sides of the vehicle, roughness might result in greater vehicle instability [26].

Examining the effectiveness of the proposed countermeasures
The effectiveness of the proposed countermeasures can be obtained through processing the iRAP methodology with the new entered variables is shown in Table 4.The results of the assessment are shown I Table 5.It can be seen that the safety level has been upgraded to four-stars in segments 00+00-28.6and three-stars in sections 28.6-30km.These results meet the goals of the united stations of improving the road safety level to 3 minimum s stars in all road networks.7. Conclusions 1.The expressway 1, part of the main transport corridor in Iraq, has been selected for this study; the selected segment is 30km road length connecting Abu Ghraib district with Fallujah City.2. The results of the risk assessment of the selected road section showed high-risk level.The run-off crashes have the highest risk level followed by the head-on crash in some segments.3. The risk-factors road attributes of run-off crashes and head-on crashes are identified to be the base of the proposing countermeasures step.The identified factors are, roadside hazards, median type, road conditions, skid resistance, poor delineation, street lighting, and shoulder and centerline rumble strips.4. Countermeasures have been proposed according to the identified risk factors; assessing the road section after implementing the proposed countermeasures has led to increase the safety level of road infrastructures.The reason is that the road characteristics can be improved to accommodate the behavior of road users and avoid mistakes that lead to an increased rate of crashes. 5. Resurfacing the road section, improving their marking, lighting, and the median types raises the safety star rating by 2 stars to reach the minimum star rating required by the UN.

Recommendations
1.It is recommended to implement all the proposals of rehabilitation proposed by the World Bank report to likelihood and severity reducing of the most common types of crashes.2. The iRAP methodology is highly recommended at road infrastructure for risk assessment.

Figure 1 .
Figure 1.The methodology of the research

Figure 2 .
Figure 2. The selected study road

Table 1 .
The road attribute table for the selected section

Table 1 .
The road attribute table for the selected section (continue) Table 2 shows the SRS results for the assessed sections.1232 (2023) 012056

Table 2 .
The SRS and SR results for the assessed section.

Table 3 .
The high-risk factor road attributes at the assessed road section

Table 4 .
The changed input variables after proposing countermeasures and their codes.

Table 5 .
The SRS and SR results for the assessed section after applying the proposed countermeasures.