It's not too surprising that lower speed limits contribute to safer roads. Research from the Insurance Institute for Highway Safety suggests this is also true for some city streets where people are already driving relatively slowly.
The data behind this study comes from Seattle, Washington, lowering the speed limit on arterial roads in the downtown area to 25 miles per hour from 30 mph previously in November 2016. In addition, the city dropped the limit on residential streets to 20 mph from the previous 25 mph.
