Simulation-Based Comparison of the Performance and Safety of Freeways with and without Heavy Gravity Vehicles Restriction

Due to an increase in goods transportation and movement of heavy gravity vehicles, high-volume freeway routes include a level of safety reduction. The aim of this study is to explore the effect of heavy gravity vehicles restriction on passenger vehicles to reduce their interactions, which is necessary for the use of special lanes or lane restriction for heavy gravity vehicles. Lane restriction for heavy gravity vehicles is a method that is commonly employed in this country, but is lacking any detailed academic studies. In addition, this paper presents efforts to determine a comprehensive and suitable criterion for specifying appropriate use of lane restrictions on a freeway or highway. In this research, the presence or absence of lane restrictions for freeways in Iran are investigated, along with a comparison of those two modes and the influence of several parameters on that process. To this end, in order to compare the scenarios, the traffic simulation software VISSIM and a section of the Tehran- Qom freeway was used as a case study. Also, in order to evaluate safety, the SSAM software was used, and to ensure maximum compatibility with the specified situation, its calibration and validity was examined. From this research, the presence of lane restrictions for heavy gravity vehicles was shown to improve operational performance by about 4%, and in terms of safety, the presence of lane restrictions was shown to be somewhat weaker than the lack of them. This conflict between operational performance increment and safety reduction based on lane restriction is related to the accumulation of heavy gravity vehicles in right hand lanes and the complications of vehicles changing lanes for exit from the freeway and entering the ramp.