Methodology for Determining Weighted Access-Density on Two-Lane Highways: Case Study of the Republic of Serbia

Abstract

Access density is a characteristic of two-lane highway sections whose role and significance in calculating the capacity and level of service in Serbia has not yet been researched. Because of the large number of access points per unit length (access density), direct applicability of the Highway Capacity Manual (HCM) methodology for two-lane highways has been called into question, as access density is one of the influencing factors. In this case study, realistic vehicle speed data were tracked using a global positioning system (GPS) device and used to generate a graph of speed versus distance traveled for each trip, and a methodology for calculating the time losses due to the maneuvering of a vehicle from/to access points is suggested. From the perspective of time losses, maneuvers that diverge from the main direction of travel were identified as the most critical and, as such, were used as the basis for a methodology for assigning a weighted value to every access, which is the fundamental objective of this paper. The model was verified by comparing the speed values obtained using the model from HCM based on both access density and weighted access density with real average travel speeds.