Traffic safety analysis using long-term accident record for merging and diverging section in Ethiopian Toll road expressway

Traffic disruptions (including frequent and abrupt lane changes in critical merging, diverging and overtaking zones) often result in expressway accidents. This study analysed crash data from the Ethiopian Toll Road Enterprise (2015-2022) using statistical and multinomial logistic regression models to identify high-risk crash locations, assess the severity and investigate the contributing factors in key merging and diverging sections. The analysis considered risk factors such as driver behaviour, traffic patterns, vehicle types, road conditions and lighting. The results indicated a 22.5% increase in accidents on wet pavements compared to dry surfaces across the entire length of the expressway, for a 2.04% increase in traffic volume. Fatalities and severe injuries were more frequent in the merging areas. Over 308 days of rainy weather across 8 years, accidents in the merging and diverging zones were 9.24% more likely to occur on wet roads than on dry surfaces. These observations highlight the increased accident risk caused by frequent and abrupt lane changes under wet conditions, emphasizing the need for improved safety measures in critical areas.