A Study of Traffic Capacity with Regards to Heavy vehicle Share and Level of Service through Microsimulation

Abstract: The 2+1-road is a specific three lane road which aims to increase the safety of the predecessor 13 meter wide four lane roads. As a lane is removed and a weaving section is introduced the capacity is severely lowered, sometimes halved. A very demanding part of the traffic system with regards to capacity are heavy vehicles, especially in conjunction with the 2+1-roads. However, exactly how the share of heavy vehicles impacts the traffic system with regards to 2+1 roads and freeways is not previously studied, which grants the opportunity of this work. The work has been carried out in connection with an assignment from The Swedish Transport Administration of analyzing the E4 going north from Gävle. This study analyzes how the share of heavy vehicles and level of service affect the speed on the two types of roads. The Swedish Transport Administration currently bases their current relationships on speed, capacity, and level of service on a share of heavy vehicles of 12%, which may give slightly wrong results depending on which system is being analyzed. The study has been carried out through micro simulation, which is a method that is very dependent on what data it is given, such as behavioral parameters and other input. The results of the study show how the relationship between share of heavy vehicles and level of service affect the speed, and that the 2+1-roads are highly dependent on the share of heavy vehicles, whereas the freeways have much larger tolerances.