THE EFFECT OF TRUCK TRAFFIC CONTROL STRATEGIES ON TRAFFIC FLOW AND SAFETY ON MULTILANE HIGHWAYS

The increased operation of trucks (defined here as vehicles having six or more wheels in contact with the road and having a gross vehicle weight greater than 10,000 lbs) on interstate and primary highways, which has been encouraged by recent legislation, has been found to affect safety and the quality of traffic flow on multilane highways. The concept of imposing certain restrictions on truck operations on multilane highways has therefore been identified as a means of reducing this effect. However, the overall impact of these restrictions on safety and traffic flow has not been fully studied. For example, either restricting trucks to a specific lane (or lanes) or imposing a lower speed limit on them, could have varied impact on traffic. The primary objective of this research is to provide information about the nature and extent of the impacts of such truck control strategies on traffic flows, speeds, headways, and accident patterns. Simulation technique was used to study the effects of implementing different strategies on multilane highways. Impacts of the strategies were evaluated and compared, and the significant changes in flows, speeds, headways, and accidents are presented. The results did not indicate any safety benefits from the imposition of any of these strategies but suggested that the potential for an increase in accident rate will be created, particularly when the strategies are imposed on highways with high volumes, a high percentage of which is trucks.