“Wider lanes were, obviously, safer than narrower ones. Only they’re not. This time, the problem with the cost-benefit equation wasn’t a faulty premise, but the data itself. In order to test the wider-lanes-are-safer-lanes hypothesis, I studied every crash that occurred on the bridge over a three-year period and marked each one on a map. If that notion had been true, I reasoned, more crashes would have occurred where the lanes were narrowest, that is, at the towers. Just the opposite turned out to be the case. The towers, it turned out, were the safest places on the entire bridge; my explanation is that when lanes get very narrow motorists drive more carefully. Even though every traffic engineer in the country had been taught the gospel of wider lanes, the opposite appeared to be true: “grossly substandard lanes seemed to be the safest of all.” This was the traffic engineering equivalent of saying the Earth was round when the masses knew it was flat. Still, most engineers do not accept this fact.”
―
Samuel I. Schwartz,
Street Smart: The Rise of Cities and the Fall of Cars