How Car Centric Planning is Killing Us

Matthew G. Saroff
2 min readNov 14, 2023

It turns out that traffic lanes vary between 9 feet (2.7 m) and 15 feet (4.6) in the United States, with the most common on city streets being 10 and 12 feet.

It turns out that 12 ft wide traffic lanes have 50% accidents than the 10 ft ones, largely because people speed more in wider lanes.

Of course traffic planners like the wider lanes because it moves traffic faster, which also kills people, which is a microcosm of US traffic management:

10 is plenty — and nine is even better.

The lightning-fast 12-foot lanes that run down countless roads in U.S. neighborhoods are associated with a roughly 50-percent higher rate of crashes than nine-foot ones, a new study finds — but many state and national design guidelines are still encouraging engineers to build them based on the false assumption that wider is safer.

The finding is a result of a painstaking Johns Hopkins analysis of more than 1,100 non-interstate street sections in seven major U.S. cities — and amazingly, it may be the first time the relationship between lane width and safety has ever been comprehensively studied on such a large scale.

Roomy roads are proven to encourage faster, deadlier driving regardless of the speed limit, but previous research based on more limited data found less correlation between gargantuan lanes and high crash rates — with some researchers and engineers even arguing that narrow roads are more dangerous because they increase the possibility of “side friction” between cars. Unlike the 129-page Hopkins paper, though, those studies didn’t go street-by-street on Google Maps and use advanced machine learning to identify and control for all the other traffic-calming features that might be cutting crashes besides paint, including the number of lanes, the curvature of the road, and the presence of bike lanes, street trees and generous sidewalks.

(emphasis original)

In Europe, the lanes are typically 8.2 feet (2.5 m) and 10.6 feet (3.25m), and pedestrian deaths and other accidents are far less.

Car friendly design is bad for the environment and kills people.

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