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A National Speed Limit

July 3, 2008 - by Donny Shaw

Yet another idea to reduce gas prices being kicked around in Congress, the Associated Press reports:

>Sen. John Warner, R-Va., asked Energy Secretary Samuel Bodman to look into what speed limit would provide optimum gasoline efficiency given current technology. He said he wants to know if the administration might support efforts in Congress to require a lower speed limit.
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>Congress in 1974 set a national 55 mph speed limit because of energy shortages caused by the Arab oil embargo. The speed limit was repealed in 1995 when crude oil dipped to $17 a barrel and gasoline cost $1.10 a gallon.
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>[…]
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>Warner cited studies that showed the 55 mph speed limit saved 167,000 barrels of oil a day, or 2 percent of the country’s highway fuel consumption, while avoiding up to 4,000 traffic deaths a year.
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>"Given the significant increase in the number of vehicles on America’s highway system from 1974 to 2008, one could assume that the amount of fuel that could be conserved today is far greater," Warner wrote Bodman.
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>Warner asked the department to determine at what speeds vehicles would be most fuel efficient, how much fuel savings would be achieved, and whether it would be reasonable to assume there would be a reduction in prices at the pump if the speed limit were lowered.

Detroit News does the math in an earlier article, figuring that a rational person would have to value their time at less than $12/hour to voluntarily choose to slow down:

>It is classic time-is-money tradeoff, said David Greene, a researcher for the U.S. Department of Energy based in Tennessee. A motorist can save $12 in gas by going 10 mph slower over 500 miles. But it adds an hour to the trip.
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>"For a lot of people, their time is still more valuable than the fuel savings," Greene said.

Of course, driving 55 on the highway is annoying enough that a mandate, not rational decision making, would be needed for people to actually begin slowing down. And there’s also a safety issue that such a mandate would solve:

>Police and others say slowing down too much can be dangerous. Some folks are tempting fate by dipping below 55 mph, said Jim Rink, a spokesperson for AAA Michigan. If most traffic is going 70 to 75 mph, the slow car becomes a danger, he said. “It’s a recipe for a potential crash,” he said.

Photo of U.S. 50, “the loneliest highway in the world,” by kla4067 used under a Creative Commons license.

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