evaluating and prioritizing the effect of human and road factors on road accidents and providing solutions (case study: northern roads of ardabil province)

A combination of various human and road factors leads to accident occurrence. by studying drivers' behavior, changing and developing geometric factors of the road, securing, and control measures, number of accidents will change significantly. this research focuses on human and road factors. based on analysis of accidents in the northern roads of ardabil province, accidents have been evaluated and analyzed using r software and the main causes have been identified. also, based on cmf and n predicted (accident number prediction) methods in the highway safety manual (hsm), the impact of lane widening, correcting some geometric factors, and converting the two-lane two-way road into a separated four-lane road on accident numbers was examined. the results of the human factors study indicate that exceeding the safe speed limit, unauthorized overtaking and the driver's failure to pay attention to the front are the most important factors in the accidents of roadways, which are responsible for more than 90% of the accidents, and the modification measures of the road geometry (such as widening and converting from two-lane to four-lane) as well as, securing the route and intersections, have a significant effect on reducing accidents. prediction models indicate that widening the route and providing an 11m width including asphalt shoulders, applying the above measures, and controlling the road with cameras will lead to a 40% reduction in accidents in the short and medium term, and converting the two-lane route into a four-lane one will result in a 34% reduction in accidents.