Effect of Truck Lane Restrictions on Four-Lane Freeways in Mountainous Areas

Several states have implemented truck lane restrictions in an attempt to improve safety and mobility on freeways. These restrictions have typically prohibited trucks from traveling in the median lane of freeways that have more than three lanes per direction. Virginia has recently implemented a new type of truck restriction that prohibits trucks traveling more than 15 mph below the posted speed limit from the left lane on four-lane interstate segments. This new restriction is primarily used in mountainous areas of the state where truck climbing lanes may be warranted but are not present. The results of a safety and operational evaluation of these truck lane restrictions were documented. Crash data were examined at 19 sites with restrictions. Likewise, operational data were collected at four sites with restrictions to assess compliance and the extent to which slow-moving trucks were impeding traffic flow. The safety analysis shows some positive trends in crash rates after implementation of the restrictions, but only the overall number of fatal and injury crashes showed a statistically significant decline. Although compliance with the restrictions was generally good, a number of slow-moving vehicles, including passenger cars, were still found to be impeding traffic in the left lane.