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The 80th percentile

The good folks of Fort Hancock, Texas, have the right idea. They have just raised the speed limit on their portion of Interstate 10 to 80 miles an hour.

In doing so, the burghers of Hudspeth County have adopted the highest speed limit in the country.

Even traditionally laissez-faire Montana finally enacted a statewide speed limit below 80.

The Hudspeth folks concluded that since the majority of people who drive through their patch of "creosote bushes, mesquite trees and intermittent cactuses" are already driving that fast, the authorities should accede to the popular will.

The Texas authorities believe that most of their drivers exercise common sense and so should they.

California's state law governing localized speed limits does almost exactly the same thing. Our law relies on the good judgment of the majority of drivers to ascertain the safe and reasonable speed for a given section of roadway.

California's Vehicle Code Section 40802 is a classic example. City and county officials are required to carry out "speed surveys and engineering studies" to provide foundation for any variation from state-mandated basic speed laws.

If they do not, their speed limit is deemed a "speed trap."

In addition, those surveys have to be current or local agencies may not use radar to enforce their ordinances.

A local speed limit may not be lower than the 80th percentile of speeds by drivers using that particular section of street as recorded in a current "speed survey." The basic notion is that 80 percent of California drivers cannot be wrong.

The law presumes that the overwhelming majority of drivers want to leave home in the morning and get home at night safely. And given that motivation, they will accurately assess the routes they are traversing and toe their accelerators accordingly.

The "engineering-study" prong of the speed-limit law allows the locals to record and factor in exceptions to the 80th percentile rule. Factors such as the adjacency of schools, businesses, on-street parking and difficult-to-see driveways may somewhat lower the speed limit.

But the baseline measure is the upper curve of the speed profile as driven by the public.

No doubt, there is the other 20 percent that have not yet wised up to the reasonable safe speed for the area. They have to be so informed by speed-limit signs and an occasional citation to remind them that what they are doing is dangerous. But that would be true no matter what the speed law.

The historic, long-simmering tension between drivers and local police departments over "speed traps" were resolved by these sorts of laws.

Drivers may have to slow down in populated areas, but only to reasonable speeds.

That was true until 1974, when the federal government decided that it had the right to impose a nationwide 55 MPH speed-limit law.

The federal rational was specious. Its claim was that driving fast wasted too much energy and therefore, in view of the latest oil crises, it had the power to limit speeds.

the government's constitutional reasoning was flawed. The power to set speed limits emerges from the police powers inherent in states. Such powers were never delegated to federal government, so the 55 MPH federal speed limit was unconstitutional as an "ultra vires" act outside of the central government's constitutional authority.

The federal speed law was "the most despised and disobeyed law ever enacted by a government," including the hated Volstead Act, which attempted to control alcohol and only resulted in creating organized crime in this country.

The law effectively made the entire U.S. highway system a "speed trap." Massive resources were wasted by states attempting to enforce a federal mandate, which caused nothing but massive contempt for such laws.

Eventually public outrage permeated Congress and in 1995 the dumb law was repealed. Instead of the carnage forecasted by such luminaries as Katie Couric on the "Today Show," highway deaths steadily declined. In 2005, the rate of injuries per mile was the lowest in the 50 years that such data has been collected.

California, Nevada, Idaho and other western states still have many miles of roads on which the speed limit is too low, making criminals out of the vast majority of people who drive them. Worse, because of the law-abiding citizens who do strictly adhere to the legal speed limit, an unnecessarily deadly mixture of prevailing vehicle speeds is engineered into the travel experience of us all.

All states would do well to enact a version of California's speed-survey statute and apply it to that state's wide-open highways.

There are of course those who know that there are too few CHP officers, and so careen through traffic at over 100 MPH.

They are the ones that kill the 43,000 Americans a year.


Stirling is a retired judge who authored the book "Leading at a Higher Level." He is a former Army officer, member of the San Diego City Council, the California State Assembly and the State Senate. Send comments to larry.stirling@sddt.com. Comments may be published as letters to the Editor.

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