Lowering the speed limit by 5 mph on city streets can improve safety for motorists, pedestrians and bicyclists alike by reducing speeding, new research by the Insurance Institute for Highway Safety indicates. Released today at the Governors Highway Safety Association (GHSA) 2018 Annual Meeting in Atlanta, Ga., the study bolsters Vision Zero efforts to reduce traffic-related deaths among all road users.
“Speeding occurs on roads of all types, not just highways and freeways,” says IIHS President David Harkey. “Even on lower speed roads, speeding can have deadly consequences, especially for pedestrians and bicyclists. Some cities are lowering speed limits to reduce the risks for these vulnerable road users, who are increasingly dying in crashes.”
The IIHS study focused on Boston, which lowered the default speed limit on city streets from 30 mph to 25 mph beginning January 9, 2017, and publicized the change via advertisements, social media and traditional media outlets. The city’s move came after the Massachusetts legislature in 2016 amended state law to allow cities and towns to lower speed limits from 30 mph to 25 mph on municipal roads in densely populated areas or business districts. Unless otherwise posted, the speed limit on all City of Boston roadways is 25 mph.
IIHS researchers looked at vehicle speeds in Boston before and after the lower limit took effect and compared them to control sites in Providence, Rhode Island, where the speed limit remained the same. The study sites in both Boston and Providence included arterials, collectors and local roads. All sites were similar in that they had no more than one lane per direction and were located away from intersections on relatively flat, straight road segments and at least a half-mile away from any school or speed feedback sign. There was no posted speed limit sign at any of the sites.
