Imagine cruising down the highway at 85 mph without getting so much as a raised eyebrow, let alone a ticket. For many drivers, it sounds like a dream, and it's set to come true on one Texas road. But we've seen this one before, and it doesn't end well.
Decades of research show that when speed limits are raised, drivers go faster and more people die in crashes. The Texas Transportation Commission's decision to establish the highest speed limit in the land on a new toll road between Austin and San Antonio means drivers there will be able to get to their destinations quickly, but at a cost.
High speeds increase the likelihood of a crash while simultaneously slashing the odds of surviving one. Crashes are more likely because, at a higher speed, a vehicle travels a longer distance in the split second it takes to react to an emergency. And the faster the vehicle is going, the further it will travel before coming to a stop after the driver slams on the brakes. When crashes occur, they are deadlier at high speeds because the energy involved increases exponentially as speed rises.
At the Insurance Institute for Highway Safety, before we rate a vehicle for frontal crashworthiness, we send it hurtling toward a barrier at 40 mph, resulting in a severe collision. Most new vehicles today do well in our moderate overlap frontal test, meaning people could survive a similar real-world crash without serious injuries. But at high speeds, all bets are off. The vehicle's structure won't hold up, and airbags and safety belts won't be able to do their job. When a crash is imminent, a car traveling 65 mph has a much better chance of getting down to a survivable speed before impact than a car traveling 85 mph.
We know that many drivers exceed posted limits, but that doesn't mean they don't take them into account. Drivers typically pick a speed at which they think they won't get a ticket — often 5-10 mph over the limit. Many Texas drivers are no doubt already used to driving 85 mph on roads with 75 or 80 mph limits. They'll read the 85 mph signs as license to go 90 or more.
The 17 years since Congress did away with the national 55 mph maximum speed limit have given us plenty of opportunities to see what happens when speed limits are raised. After the speed limit on three urban freeways in Texas was raised from 55 to 70 in the mid-1990s, we found that half the vehicles were going faster than 70 within a year, compared with 15 percent before. Seventeen percent were exceeding 75 mph, compared with 4 percent before the change.
Around the country, such increases translated into more deaths. In 24 states that raised speed limits we found 15 percent more fatalities on interstates and freeways than otherwise would have been expected.
Even with today's speed limits, speed-related crashes cause more than 10,000 deaths a year — nearly a third of all crash fatalities in the country. States could prevent some of these deaths if, instead of giving drivers permission to go ever faster, they vigorously enforced existing limits to slow drivers down.