By Chris Spahr
Paris recently made the bold move of implementing a citywide 20 mph speed limit. While some smaller cities across the globe have implemented this policy and others have put stricter speed limits on certain streets, Paris is the first city of its size to enforce a citywide 20 mph speed limit. Paris hopes to achieve across-the-board sustainability improvements through its speed reduction policies including substantially fewer crashes, significant reductions in serious injuries and deaths, energy savings, quality-of-life improvements, accessibility for local businesses, and significantly reduced carbon emissions. A 2009 study estimated a 41.9 percent reduction in road casualties as a result of introducing 20 mph zones in London. It also showed an average 8 percent reduction in casualties in areas adjacent to 20 mph zones.
Paris achieved its 20 mph speed limit incrementally by steadily increasing the number of zones reserved for pedestrians only. Paris had already posted 20 mph speed limits in its eco-quarters, communities that use energy efficient buildings and other environmentally friendly practices. The only exceptions to the Paris policy are a relatively small number of major thoroughfares into the city and along the two banks of the Seine River, where the speed limit will be 50 kph (31 mph). On Paris’s ring road, the top permissible speed has recently been reduced from 80 to 70 kph (43 mph).
Meanwhile in New York City, efforts are underway to convince lawmakers that a maximum speed limit of 20 mph can work there also. Bills from Assembly Member Dan O’Donnell and State Senator Martin Malave Dilan, introduced after motorists killed seven city pedestrians in the first 11 days of 2014, call for a maximum legal speed of 20 mph on NYC streets, except on streets “where the City Council determines a different speed limit is appropriate.” Some lawmakers are opposed to these efforts, stating that there has not been enough community involvement in the process. Frustrated by the slow pace of change in the city, residents in a Brooklyn neighborhood posted their own 20 mph speed limit signs.
As Tom Vanderbilt points out, 20 mph speed limits don’t guarantee that drivers will slow down. It is important to create “self-enforcing roads” that use design features such as narrower streets, roundabouts, speed humps, and rumble strips to calm traffic. The U.S. has a way to go to reduce traffic fatalities to the levels seen in Europe. A full-service approach that includes lower speed limits and rethinking roadway design will be required to make real progress.
Chris Spahr is a Graduate Assistant with SSTI.
By Chris Spahr