Lane Reduction Traffic Analysis

SKINNYING UP TRAFFIC

The Birmingham City Commission had a busy four-lane road with major back-ups, speed and safety concerns. Traffic studies had also showed that there was a large differential between the posted speed limit and the 85th percentile speed. Vehicles turning left on the through lane and vehicles traveling at varying speeds created havoc for pedestrians trying to cross streets along the route and for stops for buses and garbage trucks.

The Commission went ahead with a six-month pilot program, led by F&V, that reduced West Maple Road into three lanes with one lane of traffic in each direction and a center turn lane.

Results of the 1.3-mile road diet on West Maple Road between Cranbrook and Southfield roads were overwhelmingly positive. The data collected showed that all crash types were reduced by an overall average of 38% and there was a decrease in total accidents.

While the volume of traffic was unchanged, the average speed of vehicles decreased. In addition, vehicle platooning provided more gaps in traffic for vehicles on the side streets to access West Maple Road.

After the six-month feasibility study by F&V (which included modeling of the study network, crash analysis, and calculation of intersection delays, Levels of Service (LOS), and vehicle queues), Birmingham City officials decided that the road diet worked and that after repaving, the 1.3-mile stretch become a permanent three-lane roadway.