Wednesday, August 31, 2011

Europe Envy: Texas Wants High Speed Roads. Will More Texans Die in Crashes?

On September 1st Texas will be able to raise the speed limit on highways to 85 miles per hour if they can find sections safe enough. Safe, like the really flat and straight piece of road where the guy in the video below drove his $2 million Bugatti Veyron into a Texas lake. In his defense, the idiot was reaching for his cell phone.


In any event, the Texas legislature has Europe Envy! Here is what one of the statesperson had to say about raising the speed limit:
"They have high-speed roadways in Europe, and there could be some merit in having some of those highways in Texas," said Rep. Lois Kolkhorst, R-Brenham, who introduced the bill. "Given the right engineering, we should consider it."

I wonder what other policies Europe has that Texas Republicans think are worthwhile. What does Lois Kolkhorst say about high speed trains? She didn't like the Trans-Texas Corridor much.

Throwing cold water on the idea was Jerry Johns of the Southwestern Insurance Information Service:
"Obviously, the two things that kill most people on our highways are speed and alcohol. Increasing it to 85, or even 75, will have a dramatic impact on the death and injury rate on those highways where it's implemented," said Jerry Johns, a spokesman for the Southwestern Insurance Information Service.

It's true that speed and booze are the two biggest reasons that people die in cars. No one says we should drink more before we drive, so why should we drive faster?

The answer to this is a bit complicated, but there was a natural experiment in higher speed limits and fatalities when states were allowed to raise the speed limit from 55 to 65 miles per hour. (Remember, the 55 miles per hour speed limit was not chosen for safety, it was chosen and implemented to save fuel.) If speed kills, then we expect to see an increase in deaths, but that's not what happened. Charles Lave and Patrick Elias looked at the data and found that deaths went down system-wide. This counter-intuitive result was because enforcement resources were shifted from speeding infractions in remote areas to areas with greater problems. Rural deaths increased by about a third but urban deaths declined. Since there are far more miles driven in urban areas the percentage changes may distort the absolute changes in deaths. Here is their abstract:
Abstract
In 1987, most states raised the speed limit from 55 to 65 mph on portions of their rural interstate highways. There was intense debate about the increase, and numerous evaluations were conducted afterwards. These evaluations share a common problem: they only measure the local effects of the change. But the change must be judged by its system-wide effects. In particular, the new 65 mph limit allowed the state highway patrols to shift their resources from speed enforcement on the interstates to other safety activities and other highways—a shift many highway patrol chiefs had argued for. If the chiefs were correct, the new allocation of patrol resources should lead to a reduction in statewide fatality rates. Similarly, the chance to drive faster on the interstates should attract drivers away from other, more dangerous roads, again generating system-wide consequences. This study measures these changes and obtains surprising results. We find that the 65 mph limit reduced statewide fatality rates by 3.4% to 5.1%, holding constant the effects of long-term trend, driving exposure, seat belt laws, and economic factors.

So while the double nickel was saving gas it was costing lives and led to poorly allocated resources. Unintended consequences get you every time.
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