The Impact of Access Driveways on Accident Rates in Iranian Main Roads

Today, existence of several access driveways to Iranian main roads has become one of the main problems of the national roads network. As the design, operation and monitoring conditions in such roads do not match the existing standards; many dangerous spots are formed in these roads.The main goal of this research is to determine the impact of access density on accident rates in Iranian roads. For this purpose, at the first phase, the terminology of access roads, their characteristics and also design and operation parameters were taken into consideration and defined. Then, by considering road accidents trends, those parameters which directly have impact on accidents were theoretically introduced and considered. Then the descriptive statistical analysis and statistical regression models were presented in order that the relation between roads accident rate and main relevant factors causing accidents (of which we can refer to access driveways), become clear. The main results of this research are as follows:•Changes in the density of access driveways can directly affect the rate of accident with the same ratio.•Less density in access driveways will result in smoother incremental trend of accident rates.•When access density increases and passes some specific limit, the accident rates increase remarkably.•In roads where there are a lot of access driveways, after some specific maximum limits, with an increase in access density, the accident rates decrease. Therefore, there are also other important factors causing accidents, especially in roads with many access driveways.