Safety and Operational Evaluation of Truck Lane Restriction

This study was aimed at determining the operational and safety impacts of the 24-hour restriction of trucks from using the median lane of the six-lane Interstate 75 freeway corridor. The 139-mile corridor in North Florida is relatively uncongested operating at level of service (LOS) of B or better on typical weekdays. LOS is a measure of driver's freedom to maneuver in a traffic stream. The simulation analysis showed that opening all lanes to trucks increased the number of lane changing maneuvers by 11% in daytime, a phenomenon likely to increase crashes in the corridor given that the review of reported crashes showed that lane changing was a major contributing cause of crashes currently occurring in the corridor. The analysis of field data indicated that the difference between truck and passenger car speeds and travel times were insignificant on the unrestricted middle and shoulder lanes. Approximately two thirds of both passenger cars and trucks were traveling within the 10-mph pace, defined as the 10-mph speed range with the highest number of observations, that ranged from approximately 70 mph to 80 mph in the corridor that has speed limit posted at 70 mph. The field data also showed that trucks were able to use the middle lane to pass with reasonable delay during the truck peak hour period, using various gap acceptance thresholds.