AUSTIN, Texas — Not only is everything bigger in Texas, it's becoming faster, too.
This week, if all goes according to plan, the posted speed limit on more than 500 miles of West Texas interstates will rise to 80 miles per hour. That will make Texas home to the highest posted limit anywhere in the United States and one that will rival the recommended maximums on Germany's famous autobahns.
The Texas Legislature fast-tracked the increased speed limit last year and unanimously recommended it; then the Texas Department of Transportation followed suit with feasibility studies that gave the green light. The Texas Transportation Commission gave its approval Thursday.
The first new speed limit signs went up along two flat, rural stretches of Interstates 10 and 20 just in time for Memorial Day, the traditional start of the summer driving season.
Texans brush aside such concerns as fuel efficiency or the cost of gasoline.
Engineers calculate that drivers burn 7% more gas per mile for every 5-mph increase in speed above 60 mph. Texans calculate that their Hummers need bigger gas tanks.
"Our mission is to go and seek out whether we can fulfill the requests of the driving public," said Mark Cross, spokesman for the state transportation department. "And the request from the public is they want to go faster."
Texas and 11 other states permit drivers on some highways to travel up to 75 mph, according to the Insurance Institute for Highway Safety. But Texas transportation engineers determined that 85% of drivers on the two segments of I-10 and I-20 were averaging 80 mph, 5 mph above the current 75-mph speed limit, so officials reasoned that raising the limit would simply be a bow to reality.
"We feel it's always safer to have motorists traveling at a more uniform speed," Cross said.
It turns out that 85% is something of a magic number in traffic engineering circles: The speed at which 85% of drivers are traveling, regardless of the posted speed limit, is considered to be the optimum "natural" speed for any given stretch of roadway. The assumption is that a majority of drivers, if left to their own speedometers, will collectively achieve a safe operating speed, and that speed should be the primary factor in setting the legal limit.
This is not, however, a particularly popular notion among traffic safety experts.
