Identifying Impact of Truck-Lane Restriction Strategies on Safety by Using Simulation

The continuous growth of freight transportation over the recent years has resulted in an increasing proportion of commercial vehicles on our nations’ highways. This has led to higher truck volumes and severer truck-related crashes every year. Safety proponents have therefore been advocating for more restrictions to be placed on these commercial vehicles, in order to reduce the interaction of these larger vehicles and passenger cars. A popular strategy is the use of different lane restrictions for trucks. However, the impact on flow and safety of these restrictions differs from one site to the other because of the unique conditions at each site, including the type of restriction used, the traffic conditions and the geometric characteristics at the site. This study evaluated the impact of these restrictions on the traffic operation and safety for several combinations of traffic and geometric characteristics. In this paper, we present the results obtained for the safety impact. Due to the limited availability of site data, the evaluation was conducted through simulation, using the PARAMICS V3.0 (Quadstone Ltd., 2000) program with its advanced Application Program Interface (API) functions that simulate the different traffic and geometric characteristics. The measurement of effectiveness (MOE) for safety employed in this study is conflict, a surrogate measurement for traffic crash. The impact of different lane restrictions in terms of the above MOE was evaluated for different traffic conditions (volume, truck percentage) and geometric characteristics (gradient, speed limit, intersection density). ANOVA analysis of the simulation results indicates that truck lane restrictions show significant impacts upon all kinds of conflicts related to trucks.