Evaluation of the Pavement Distress and its Impact on the Sustainability of the Traffic Operation for Selected Roads in Al-Diwaniyah City

Roads and transportation infrastructure are critical assets for supporting political stability as well as economic and sustainable expansion in developing countries. Yet, pavement maintenance backlogs and the high capital expenditures of road rehabilitation need the adoption of pavement evaluation methods to ensure the best value for the investment. road maintenance is considered one of the main factors for preserving the road structurally and functionally, and before carrying out maintenance, pavement defects must be identified by evaluating the condition of the pavement to perform the appropriate maintenance. In this study, the Pavement Condition Index (PCI) method was relied upon to evaluate roads in Al-Diwaniyah City. Where several data were collected for the study, including the number of crashes for each region, the number of lanes, street width, the presence of a median, and the pavement condition evaluated for the regions with the highest crash rate, which are Al-Askari District with 707 crashes, Al-Urouba District with 379 crashes, Al-Wahda District with 271 crashes, Al-Jamhouri District with 235 crashes, and Al-Jazaer District with 212 crashes. This study is considered the first study to evaluate roads in Al-Diwaniyah city. The results of the study showed that the condition of the roads ranged from poor to satisfactory and there is no road reach to serious and failed. The results showed that the worst road is Al-Askari District, which lacks a lot of maintenance, at a rate of PCI 52.1. It is followed by Al-Wahda District with a PCI rate of 57.6, Al-Jamhouri District with a PCI rate of 67.2, Al-Urouba District with a PCI rate of 70.7, and Al-Jazaer District with a PCI rate of 73.7. The deterioration of the pavement surface condition affects the rash rate, and it is more dangerous when it is correlated to other road factors. Additionally, it was noted that the most prominent defects in the pavement surface of the five evaluated roads are: potholes, rutting, longitudinal and transverse cracks, corrugation, patching, raveling, depressions, and alligator cracks. The study recommended conducting more research on evaluating more roads in Al-Diwaniyah City on an annual basis and conducting periodic maintenance in order to improve the status of this city, which suffers from neglect in all respects, measures must be taken to enhance the environment and economy, sustain the streets, reduce maintenance costs, ensure traffic safety, and protect the lives of citizens.


Introduction
Transportation infrastructure is critical for emerging countries' political stability and economic progress.Yet, backlogs and hefty maintenance costs define those countries' roadway infrastructures.As a result, road authorities require adequate procedures and methodologies for survey data processing in order to build strategic business plans for future expenditures based on pavement condition evaluations.Road systems are an essential factor in the development and growth of countries in the world, so it is important to maintain them in a way that guarantees smooth movement of vehicles, ride comfort, and traffic safety to avoid traffic crashes.Road functions are preserved through good construction and periodic maintenance of roads, before every maintenance for roads, should have an evaluation of the road condition and knowledge of defects and causes to carry out appropriate maintenance to prevent deterioration of the surface resulting from heavy and repeated traffic loads or environmental factors.The pavement Condition Index (PCI), which is an indication of the status of the surface road, is one of several ways to analyze the road's condition.PCI is a visual survey that provides a numerical range from 0 to 100, where 0 represents the worst road condition, with greater surface road distress, and 100 represents the best road condition, with less pavement distress.The PCI assesses the amount, severity, and type of pavement surface distress [1].A study in Iraq's Nasiriyah city evaluated 13 deteriorated streets in the Al Hadharat area using the (PCI) pavement condition index and recommended acceptable maintenance strategies.The study's findings revealed the (PCI) categorization values ranged from fair, poor, and very bad, with one instance being serious.The study explored the (PCI) method as an adequate and effective way of diagnosing road faults and evaluating pavement quality to perform and select necessary pavement repair [2].In another study, researchers conducted a study on some roads in the province of Najaf in Iraq to evaluate them based on the pavement condition indicator, where data were collected for each of the streets Al-Rahma, Al-Hizam Al-Akhdar, and Al-Muearid, Al-Shamalii garage highways, as the results were that Al-Shamalii and Al-Rahma garage roadways segments were at a satisfactory level, the Al-Muearid roadway segment was fair, and Al-Hizam Al-Akhdar was poor [3].A study in Brazil to find out the damaged paths in the state of Paraná by using the PCI method.A subjective and objective assessment was conducted and compare between them using the Pearson correlation coefficient, where 92.21% of the passages were classified as being in very good to good condition, while 7.94% were classified as poor to very bad.The result was that there is a substantial correlation between objective and subjective evaluation, where PCI can be used simply and easily through subjective evaluations, as it is a method that has good results for pavement roads [4] [5] [6].A study in Al-Hillah Governorate in Iraq to assess the condition of the main road through which a comparison was made between the PCI method and the traditional method by conducting laboratory tests that require a lot of effort and cost, and using the core test.The road despite the difference in the method of expression in the two methods, the reasons for the defects mentioned by the standards of the PCI method in the discussion are the same reasons indicated by the results of laboratory tests [7] [8].Another study was conducted to evaluate Thamrin Street in Indonesia using Pavement Condition Index (PCI) method.the study showed 70.8% of (PCI) and classified the state of pavement as good and the study recommended in routine maintenance for the road [9] [10].

Location of the Study
Al-Diwaniyah city is one of the Iraqi cities located in the Middle Euphrates region, with an area of 8153 km 2 .It is considered one of the lower income cities from an economic point of view.It also lacks pavement maintenance, and therefore the pavement deterioration, which causes great risks to traffic safety on the roads, especially in some areas, including the al-Askari district, Al-Wahda district, Al-Jamhouri district, Al-Urouba district, Al-Jazaer district.These areas are located in the center of Al-Diwaniyah City and are used in the process of transporting goods and people, and traffic crashes are frequent in them [11].Therefore, it is important to evaluate the condition of these roads to identify the appropriate maintenance methods and treat pavement defects to maintain a high level of service across the whole network.Figure (1) shows the location of Diwaniyah city on the map of Iraq and the residential areas within the city.

Data Description
The study area was chosen based on the number of crashes recorded for each road.In this study, 5996 crashes were obtained for the internal roads registered in Al-Diwaniyah Hospital due to the lack of information and data available in the General Traffic Department regarding traffic crashes for the internal roads in the city, the data were obtained for the years from 2014 to 2021.and the regions with the highest percentage of crashes were chosen.Thus, the total data that was studied is 1804, especially for these five regions.Al-Askari District ranked first in the number of crashes with 707 traffic crashes, followed by Al-Urouba District with 379 traffic crashes, Al-Wahda District with 271 traffic crashes, Al-Jamhouri District with 235 traffic crashes, Al-Jazaer District with 212 traffic crashes.Therefore, it is important to evaluate the condition of pavement in these Districts where the number of traffic crashes is high to know the effect of pavement defects on the accident rate [12] [13] [14].other road information such as the number of lanes, the presence of medians, and street width was collected to study their effect on the condition of the pavement and the number of crashes.Figure 2 shows the location of the studied areas in evaluating the road surface condition using Google Earth.The condition of the road surface on these five roads was assessed using the PCI method based on the American specification for the year 2018.(D6433 -18) ("Standard Practice for Roads and Parking Lots Pavement Condition Index Surveys") [15].

Methodology
The method of pavement condition index has been adopted in this study to assess the pavement condition and identify the most prominent existing defects.The road was divided into sections every 100 meters in length and the most prominent defects in each section were identified, where the type, severity, and dimensions of each existing defect were recorded, then the density was calculated by dividing the area of the defect by the area of the section, which is equal to the (length of section 100 * the width of the road).
Measuring tools used to measure pavement surface defects were a tape measure and a ruler.Then the deduced values (DV)are determined for each density percentage, by projecting the percentage with distress severity into special forms for each defect according to the American Standard Specification.Taking into account the calculation of the value of the allowed number of the deduction (m), which must be less than or equal to 10, which includes the friction part, according to equation (1) m= 1+ (9/98) (100 -HDV) ≤ 10 ……………………… (1) m: The allowable number of deducts including fractions (must be less than or equal to ten), HDV: The highest individual deducts value.That is, if m is greater than the number of defects in the section, then the smallest value of the extracted deduction values is reduced depending on m.After that, the work starts progressively by decreasing the deduced values greater than (2) from the smallest value until we reach one value of the discount values greater than (2).A total deduced value (TDV) for each stage has been found, then project the TDV with q (number of deducts with a value greater than 2.0) to determine the corrected deduct value (CDV).Then the maximum corrected deduct value (CDV) used to calculate (PCI) that can be calculated through the following equation: The state of pavement is determined for each section from failed to good depending on Figure (4) below, and then find the average for all sections of one road and each district separately.

Data Analysis and Evaluation
The dimensions and area of all road surface defects were calculated for each study area according to the standard specification.A sample of the sections that were worked on will be mentioned for abridgment.

Al-Askari District
The pavement condition was evaluated for all the main roads in the region, with a length of 4,500 km, a width street of 6.7 meters, and two lanes.Al-Askari district does not contain a median.the road was divided into segments every 100 meters, and an evaluation was conducted for each segment, and then the average was calculated.In the section from 0 to 100 value of PCI is 50 and classified as poor according to the standard specification as shown in Table (1).The other sections of the Al-Askari district are classified from very poor to poor and a few sections were recorded as fair.So, the PCI of the average sections of roads is 52.1 and classified as poor.Any weakness in the design of the asphalt mixture leads to the failure of the structure, especially when applying heavy loads to the pavement, as it leads to the formation of cracks and other pavement defects.The studies showed that heavy vehicles worsen the condition of pavement and thus increase road maintenance costs compared to the weights of legal vehicles [16] [17].or others cause moisture damage, including loss of adhesion and cohesion between the asphalt and aggregate grains; consequently, the loss of bonding leads to the separation of the components of the asphalt mixture, the deterioration of the pavement surface, and the failure of the road [18].

Al-Wahda District
The pavement condition was evaluated for all the main roads in the region, with a length of 1100 meters, a width street of 12 meters, and three lanes.Al-Wahda District does not contain a median.the road was divided into segments every 100 meters, and an evaluation was conducted for each segment, and then the average was calculated.In the section from 0 to 100 value of PCI is 54 and classified as poor according to the standard specification (see Table 2).The other sections of the Al-Wahda District are classified as very poor, poor, fair, and satisfactory, So the PCI of the average sections of roads is 57.6 and classified as fair.
In some cases, several roads even failed structurally, within half a year after opening to traffic due to Poor construction quality has been a significant contributor to this issue [19]- [21].

Al-Jamhouri District
The pavement condition was evaluated for all the main roads in the region, with a length of 1600 meters, a width street of 10 meters, and three lanes.Al-Jamhouri District has a median.the road was divided into segments every 100 meters, and an evaluation was conducted for each segment, and then the average was calculated.In the section from 0 to 100 value of PCI is 67 and classified as fair according to the standard specification as shown in (Table 3).The other sections of the Al-Jamhouri District are classified as poor, fair, satisfactory, and good.So, the PCI of the average sections of roads is 67.2 and is classified as fair.

Al-Urouba District
The pavement condition was evaluated for all the main roads in the region, Al-Urouba District which is three lanes and has a median.Al-Urouba District includes three main ways which are the first Urouba with a length of 3600 meters and a width of 7.6 meters.The second Urouba with a length of 1300 meters and a width of 10 meters.The third Urouba with a length of 2000 meters and a width of 10 meters.The roads were divided into segments every 100 meters, and an evaluation was conducted for each segment, and then the average was calculated.The PCI value in the section from 0 to 100 of the first Urouba is 81 and classified as satisfactory (see Table 4).The PCI value in the section from 0 to 100 of the second Urouba is 46 and classified as poor (see Table 5), and The PCI value in the section from 0to100 of the third Urouba is 90 and classified as good (see Table6).The other sections of the Al-Urouba District are classified as poor, fair, satisfactory, and good.So, the PCI of the average sections of roads is 70.7 and is classified as fair.

Al-Jazaer District
The pavement condition was evaluated for all the main roads in the region, with a length of 4100 meters, a width of 10.6 meters, and three lanes.Al-Jazaer District has a median.the road was divided into segments every 100 meters, and an evaluation was conducted for each segment, and then the average was calculated.
In the section from 0 to 100 value of PCI is 71 and classified as satisfactory as illustrated in Table (7).The other sections of the Al-Jazaer District are classified as fair and satisfactory.so, the PCI of the average sections of roads is 73.7 and is classified as satisfactory.

Conclusions
Pavement distress can have a significant impact on sustainability.Poorly maintained roads can lead to increased fuel consumption, increased emissions, and higher maintenance costs.Additionally, pavement distress can lead to increased safety risks for drivers pedestrians.By addressing pavement distress in a timely manner, cities and municipalities can reduce their environmental footprint and improve the sustainability of their transportation networks.For that, pavement condition is one of the main factors that cause crashes and increases its seriousness as a result of defective construction or poor maintenance that Diwaniyah city suffers.The establishment of rules for the creation of rehabilitation and maintenance strategies for the homogeneous sections would aid in decision-making at the network level.The suggested method of using pavement condition indicators gives data for predicting maintenance and rehabilitation methods for road segments.The indicators can be used to assess the projected benefits of network maintenance interventions.As shown in the above table : 1. Al-Askari District recorded the largest number of traffic crashes, with 707 crashes as a result of the poor condition of the pavement, with a PCI value of 52.1, and it was classified as poor.This gives an indication that the pavement condition is deteriorating and needs maintenance due to many defects in the road surface, and it was noticed that the pavement in part of the sections is dislodged, perhaps as a result of a defect in the asphalt mixture, increased moisture infiltration into the pavement layers, or due to heavy traffic loads, and this leads to the separation of aggregate particles and asphalt binder.Other road characteristics that were lacking in the Askari District, such as the lack of a median, the number of lanes, and the width of the street, which was not commensurate with the road's capacity, have an influential role in increasing the number of traffic crashes, which caused a lot of congestion and other problems, which also increased the deterioration of the pavement condition.2. The value of PCI for the Al-Wahda District is 57.6 and it was classified as fair according to the limits of the approved standard specifications.This value is an indication of the presence of many defects on the road, and it is somewhat close to the Askari District, but when comparing the number of crashes in this area with the Askari District, it is less than the Askari District by 271 crashes, despite the convergence in the PCI value in both regions.It may be due to road factors such as the number of lanes and the width of the road, which were satisfactory, in addition to other factors that affect the increase in the number of traffic crashes.3. PCI values were recorded as 67.2 on Al-Jamhouri road and 70.7 on Al-Urouba road.This is due to the slight improvement in the condition of the pavement surface.the number of crashes in Al-Jazaer district is significantly low which is 212 crashes as a result of the satisfactory pavement condition, as the highest value of PCI was recorded in this study, which is 73.7, and suitable design for road characteristics.As a result, it was observed that pavement conditions and deterioration have a negative impact on the number and severity of traffic crashes.This affects the driver's behavior and the loss of control over the vehicle.The other characteristics of the road, which are the number of lanes, the width of the street, and the presence of a median, have an impact on the condition of the pavement, as the shorter the width of the street or the smaller the number of lanes, this causes traffic congestion and thus increases the applied traffic loads on pavement surface that lead to the failure of the pavement surface and the formation of cracks and thus infiltration of water, and this leads to an increasing number and size of defects over time.Thus, it is negatively reflected in the number of crashes.

Recommendation
The study recommends, 1-Maintaining street cleaning in Diwaniyah city and removing waste daily.2-Carrying out periodic maintenance of roads and resurfacing asphalt pavement using modern means.treating pavement defects using different maintenance methods for each pavement defect.
As shown: x Alligator cracks: If small, localized fatigue cracking indicates a lack of subgrade support, Remove the cracked pavement; dig out and replace the region of poor subgrade; and, if necessary, enhance the drainage in that area.Or patch over the restored subgrade.if extensive fatigue cracks indicate widespread structural collapse, Spread a hot mix of asphalt over the entire pavement surface.x Corrugation: If there are minor corrugated areas, patch the destroyed pavement.If significant corrugation, which indicates overall HMA failure, remove the deteriorated pavement and replace it with new pavement.x Depressions: repaired by removing the damaged pavement and then excavating and repairing the area of substandard subgrade, then applying a patch to the repaired subgrade.x Longitudinal and Transverse cracking: If there are occasional minor cracks (1/2 inch wide), the crack sealer to prevents water and moisture from entering the crack.If there are severe cracks (more than 1/2 inch in width and numerous), remove the damaged pavement layer and replace it with a new overlay.x Potholes: remove all fractured pavement and repair it.
x Rutting: If minor ruts (less than 1/3 inch deep), can be left untreated.Pavement with deep ruts must be leveled and overlaid.x Raveling: removing and replacing after any subsurface drainage problems have been corrected.
x Patching: structural or nonstructural overlay.
3-not leaving the manhole cover open or creating it in a way that impedes the movement of vehicles, as it was seen on many roads, as it looks like a hole or patch that hinders traffic and causes congestion because it was not constructed correctly.and drain rainwater and sewage.4-Evaluating the other internal and external roads in Diwaniyah city using the PCI method, which has been shown in many studies to be effective due to its ease, simplicity, and low cost in determining road distress and performing appropriate maintenance.

4 Figure. 2
Figure.2 Study Area from Google Map

Table 1 .
The Section (0-100) Meter of the Road Al-Askari District

Table 2 .
The Section (0-100) Meters of the Road Al-Wahda District

Table 3 .
The Section (0-100) Meters of the Road Al-Jamhouri District

Table 4 .
The Sections (0-100) Meters of the Road First Al-Urouba District

Table 6 .
The Sections (0-100) Meters of the Road Third Al-Urouba District

Table 7 .
The Sections (0-100) Meters of the Road Third Al-Urouba District

Table 8 .
Summary of the State of Roads in the Study Areas in Diwaniyah city