Injury Severity Analysis of Nighttime Work Zone Crashes

Egypt's National Road Project is a large infrastructure project aiming to upgrade 2500 kilometers in the road network as well as constructing 4000 kilometers of new roads to meet today's need. The road construction work inevitably leads to an increased number of work zones on highways, creating more hazardous situations for drivers. This is the reason highway agencies are shifting towards night construction work in order to reduce the traffic impacts on the public. Nighttime traffic is commonly characterized by lower traffic volumes, higher speeds and reduced visibility, but there are only a few studies providing valuable results on nighttime work zone crashes. Data from long-term Egyptian highway work zone projects that occurred between 2010 and 2016 are investigated and the injury severity of nighttime crashes is modeled by a mixed multinomial logit model. The estimation procedure indicates that the speeding factor is best modeled by a random variable. From investigation of the model parameters and their pseudo-elasticity, the influence of a wide range of risk factors on injury severity can be assessed and interpreted in terms of driving conditions. It is found that highly influential factors increasing the crash fatality risk include weather conditions (rain) and driver characteristics, such as gender and age group. Additional risk factors are vehicle type (passenger cars or heavy vehicles) and work zones with multiple lane closures.