Analysis And Modeling To Determine Contributory Factors Of Work Zone Crashes In Egypt

Egypt's National Road Project is a large infrastructure project which aims to upgrade 2500 kilometers of road networks as well as constructing 4000 kilometers of new roads to meet the needs of today.Increasing the amount of highway construction inevitably leads to a significant increase in the number of work zones and therefore a rise in more hazardous traffic conditions.Thus,it is important to ensure safety and efficient flow of traffic during maintenance and construction activities.Hence,investigating and identifying significant contributing factors and characteristics associated with the injury severity of work zone crashes is absolutely necessary.For the study objectives,available Egyptian work zones crash data were analyzed.Data consisting of work zone crashes that occurred in Egyptian long-term highway maintenance and rehabilitation projects between the years 2010 and 2016 were used to analyze crash injury severities.The objectives were achieved through carrying out the following steps.First,a descriptive statistical analysis was conducted to examine the characteristics of work zone crashes.After this,factor analysis was used to identify the main and common factors that influence work zone crashes and to calculate the weight of every factor.An ordered probit model based on the results of factor analysis scores was used to determine the significance of each factor.Separate mixed logit models were utilized to determine significantly influencing factors on injury severity following daytime and nighttime collisions.Finally,ordered probit regression analysis was conducted to identify significant risk factors contributing to the crash severities for multi-and single-vehicle work zone crashes.Based on the factor analysis results,the most influential factors contributing to work zone and work zone rear-end crashes are gender,road character and speed.Moreover,the proportion of 52.6% risk variance in work zone crashes could be explained by four factors while 65.9% of the risk variance in work zone rear-end crashes could be accounted for by five factors.The mixed logit models results indicate that significant differences exist between factors contributing to injury severity.Four variables are found significant only in the nighttime model and four different variables significant in the daytime model.The results show that older and male drivers,the number of lane closures,sidewise crashes,and rainy weather have opposite effects on injury severity in nighttime and daytime crashes.In addition,the results of the ordered probit model show that the nighttime,weekends,passenger vehicles and rural areas variables significantly increase single-and multi-vehicle crash injury severities.Furthermore,young and male drivers and foggy weather have opposite effects on injury severity in single-and multi-vehicle crashes.The findings of this study might assist transportation authorities and offer ideas for stakeholders and traffic engineers in developing effective countermeasures to reduce the occurrence and severity of work zone crashes in Egypt.