The research looked at crash databases in Tokyo and Toronto
City streets would be safer if their lane widths were reduced, according to a recent study. The standard today in most U.S. cities is 12-foot-wide lanes. A paper to be presented at the Canadian Institute of Traffic Engineers annual conference by Dewan Masud Karim presents hard evidence that these lanes increase the safety risk on city streets when compared to those at about 10.5 feet in width.
Karim’s review of existing research and an examination of crash databases in Tokyo and Toronto took into consideration 260 randomly selected intersections in the two cities. He found that collision rates escalate as lane widths exceed about 10.5 feet. Roads with lanes that are 12 feet or wider were associated with greater crash rates and higher impact speeds.