The Built Environment and Traffic Safety

TLDR

The study attributes safer dense urban traffic to lower per‑capita mileage and slower speeds, and to less‑forgiving designs that give drivers clearer cues about safe operating speeds. Contrary to conventional theory, dense urban environments are safer than suburbs, and less‑forgiving design features such as narrow lanes, traffic‑calming measures, and street trees improve safety.

Abstract

The article reaches two conclusions counter to accepted transportation engineering theory. First, the traffic environments of dense urban areas appear to be safer than the lower-volume environments of the suburbs. The reason is that many fewer miles are driven on a per capita basis, and the driving that is done is at lower speeds that are less likely to produce fatal crashes. Second, at least in dense urban areas, less-“forgiving” design treatments—such as narrow lanes, traffic-calming measures, and street trees close to the roadway—appear to enhance a roadway's safety performance when compared to more conventional roadway designs. The reason for this apparent anomaly may be that less-forgiving designs provide drivers with clear information on safe and appropriate operating speeds.