Why Don’t Speed Limits Make Sense?
I have often wondered why speed limits and the speed of traffic seem so disconnected. Most of the time traffic is moving five, ten or fifteen miles per hour faster than the posted speed limit. I have heard supposedly knowledgeable people say “no matter what the speed limit is, drivers will always drive ten miles per hour over that limit.” I’ve wondered, so if the limit was 100 MPH would everyone drive 110 MPH? I don’t think so, I know I wouldn’t come close to driving 100 MPH, even if it was legal. That tells me there is a point where motorists curtail their speeds, regardless of the speed limit.As it turns out, I was right.
After researching federal, state, and university studies I learned that speed limits work if they reflect the speeds normal responsible people typically drive on any particular road or highway. If most of the traffic on a given road travels between 50 and 55 miles-per-hour and the speed limit is set at 55-MPH almost all the traffic will be in compliance with the speed limit. If the speed limit is set at 45-MPH traffic speeds will remain at 50 to 55 miles per hour and almost everybody will be in excess of the speed limit.
Traffic engineering experts have found that most of us drive at speeds we feel are safe and comfortable for the existing conditions. If it’s clear and sunny we drive faster. If it’s raining or snowing we slow down. If we’re on a multi-lane Interstate we speed up. If we’re on a city street or winding country road we slow down. This isn’t magic, it’s just self-preservation and common sense at work.
Reality turns out to be quite the opposite of prevailing opinions. It’s not that we all drive 10 miles-per-hour over the speed limit. Rather, the problem is that speed limits are set 10 miles per-hour-slower than most people drive. The solution seems obvious, set speed limits at levels that represent existing normal (free flowing) traffic speeds and traffic speeds will be in sync with speed limits. This may upset the fans of command and control government, but we’ve tried their approach and it doesn’t work. Let’s use the knowledge we’ve gained and set rational speed limits that reflect the actions of normal responsible drivers.
