Improving the geometric characteristics of road infrastructure to reduce the rate of run-off and head-on crashes

Road risk assessment is an important strategy recommended by global organisations to avoid the road accidents occurring and reduce the likelihood of road accidents. It can be done in the design and construction stages as it is based mainly on the geometric characteristics of roads and it is not based on the road accidents history in the assessed roads. In Iraq, a few studies have been conducted to consider the road attributes in studying road safety and assess the level of road risk based on the road geometric characteristics. Therefore, it is aimed in this paper to assess road risk levels according to the road attributes and other factors such as traffic characteristics. It is focused on two types of crashes, run-off and head-on. The main steps followed in this paper are selecting the study area, collecting the needed data that represent the geometric features of roads and supporting traffic data, processing the selected methodology for assessment, presenting the results of the assessment which are presented in terms of the likelihood score, severity score, star rating and the estimated rate of fatalities. Based on the results of assessments, countermeasures are suggested to improve the safety level. The results show that poor road condition has led to high likelihood scores of both types of crashes. In addition, the unpaved roadside has led to a high severity score of run-off crashes, while the undivided road has led to a high severity score of head-on crashes. Therefore, it is suggested to resurface main roads, pave shoulders and upgrade the road section to a divided multilane road with a safety barrier median. The results of processing data after implementing each proposal show that resurfacing can save about 70% of the likelihood scores and fatalities rate, but the star rating is still at its lower level. Paving shoulders can eliminate a high rate of the severity of run-off crashes while widening and building a wide median can eliminate the severity of head-on crashes. A 5-star road for head-on crashes can be achieved by widening the road and building a wide concrete median. However, the star rating is still low for run-off crashes; therefore, it is recommended to improve driver behaviour to enhance road safety.