It’s the summer driving season in Texas and one of the busiest driving weekends of the year. This month also marks the 20th anniversary of Congress repealing the National Maximum Speed Law, which set speed limits across the country to a maximum of 55 miles per hour.
The repeal of the nationwide speed limit in 1995 was a triumph of good engineering over good intentions and has improved safety on our roads.
But that was then, and this is now. Nowadays, artificially low speed limits actually make roads less safe. In fact, on many roads in Texas and across the nation, the speed limit ought to be raised.
The 55 mph speed limit was well intentioned. It was enacted during the oil shortages of the 1970s, and it was hoped that this law would improve safety as well as reduce fuel consumption. However, good intentions aren't good enough, and in this case the problem was that few drivers actually obeyed the reduced speed limit.
Research shows that the speed limit has little effect on how fast people drive. Traffic engineers have tried all kinds of tricks — flashing lights, pink signs, cute speed limits such as 48 instead of 50 — and they all work only for a week or two until the novelty wears off.
While many drivers ignore speed limits altogether, others do try to follow them out of a sense of safety or obedience.
This difference in speeds is actually more dangerous than if everyone were driving at a faster speed. We've all felt the frustration of being behind slow drivers and annoyance at aggressive drivers weaving through traffic. Both of these situations are dangerous and make traffic worse.
Laws should not make people choose between what is legal and what is safe. Instead, let's put some trust in drivers. Although we all like to complain about other drivers on the road, the fact is that almost all of us get where we are going each day without an accident. Most of us are perfectly capable of finding a safe speed to drive at even without a speed limit sign.
Take, for example, Texas 130 between Seguin and Mustang Ridge. It has the highest speed limit in the nation, 85 mph. This doesn’t mean that everyone has to drive this fast, but that the road is designed to be safe at that speed and that drivers are free to select a safe and comfortable speed within a wide margin.
Current best practices in transportation engineering — supported by extensive research by organizations such as the Federal Highway Administration, the National Cooperative Highway Research Program and the Institute of Transportation Engineers — is that speed limits should be set at the 85th percentile of traffic speed. That is, only about 1 out of 7 cars should be driving faster than the speed limit. Any more than that and the speed limit should be raised.
Raising the speed limit also has other benefits.
It improves credibility of the speed limit sign if it consistently marks a reasonable speed for most drivers, not the speed at which politicians wish they would drive.
It also improves relations with law enforcement. Rather than having to reflexively brake when seeing a police car, or worrying about selective enforcement of speed laws when everybody is traveling over the speed limit, rational speed limits mean that average drivers can simply go about their business. No one should have to worry about being pulled over for driving in a safe manner.
And finally, it improves respect for the law. Speeding should be seen as a serious matter, not a routine offense most of us commit every day.
The bottom line is that speed limits should conform to drivers, not the other way around. When it comes to safety on our roads, good intentions are not good enough.
Stephen Boyles is an assistant professor in transportation engineering at The University of Texas at Austin.
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