Road Diets Are Cheap, Easy, and Critical to Safety

A new study finds that metro areas can reduce traffic crashes by 19 percent on busy arterial streets by imposing a road diet. A road diet reduces the number of lanes dedicated to car traffic, widening the space (and hence improving safety) for cyclists, pedestrians, and street parking. It is an antidote to the previously popular policy of widening arterial roads to accommodate increasing numbers of commuters.

"The original thinking held that wider roads meant better traffic flows, especially at rush-hour, but new lanes also attracted new traffic, and outside the peak periods you'd end up with lots of wasted road space," writes Eric Jaffe.

The case study is a cost-benefit analysis of Livingston Ave in New Brunswick, N.J., "an oversized arterial corridor accessing the center of the city." It comes on the heels of a traffic collision involving three students, who were seriously injured as a result. New Brunswick is home to Rutgers University, and the four-lane street has thousands of rush-hour commuters as well as many pedestrians. Drivers mostly ignore the 25 mph speed limit.

"What makes the situation in New Brunswick so much more regrettable is that city leaders knew about the safety hazards on Livingston Avenue but hesitated to change traffic patterns for fear of offending drivers," Jaffe laments.

Jaffe provides a nice graphic illustrating the simple and cheap road diet alterations proposed. According to the study, the costs are mostly political; research demonstrated that the level of service for drivers increased only modestly after a road diet. Jaffe finds: "All told, the traffic impacts amounted to two or three minutes of total delay and maybe one or two more minutes of travel time, depending on morning or evening rush hour and the precise configuration of the road diet[.]"