Investigation on the role of traffic volume in accidents on urban highways
Esmaeel Ayati ⁎, Ehsan Abbasi
Introduction: Roadway safety is a major concern for the general public and public agencies, as roadway crashes
claim many lives and cause substantial economic loss each year. In Iran, a large number of vehicles are
involved in road accidents each year, which cause many deaths and extensive property damage; such
accidents are among the major causes of death and disability in the country. Method: To reduce roadway
accidents, the factors that affect the occurrence and severity of accidents should be scrutinized to prevent or
reduce their effect. The method that many researchers have adopted to determine the effective parameters
surrounding road accidents in recent years is through statistical modeling of accidents. In this article, the role
of different kinds of vehicles in traffic flow are investigated separately in terms of the likelihood of crashes on
urban highways, and the vehicles are divided into three groups: passenger cars, heavy vehicles, and light nonpassenger
car vehicles. Poisson and negative binomial (NB) regression models were applied to model the
accidents in this research, which were categorized into two groups: no injury (property damage only)
accidents and more severe (injury and fatal) accidents. Results: Ultimately, we conclude that light nonpassenger
car vehicles (i.e., taxis and motorcycles) play the largest role in the occurrence of crashes on urban
highways for both types of accidents