Ever been on the freeway, going the speed limit, and glance into your rearview mirror to see only the grill of tractor-trailer semi? Who hasn?t had such a frightening vision?

There is a debate raging in Washington over a proposal to require big commercial trucks to be equipped with special devices to govern their speed. The powerful American Trucking Association supports the idea, but conservatives and many independent truckers are opposed.

The opposition correctly points out that most crashes involving big rigs are caused by drivers going faster than conditions dictate, not that they are exceeding the posted speed limit. Thus, governing the speed of a semi has little correlation to avoiding crashes.

Another opposition argument focuses on the fact that truckers sit in their cabs all day, watching passenger vehicles roar past at sometimes 20 or more mph over the posted limit. If truck speed is to be mechanically determined, they say, so should the speeds of all vehicles on the highway.

Those are valid points, but they sidestep the reality that big rigs weigh tons more than passenger vehicles, are much more difficult to stop and/or maneuver around dangerous situations, and when one of these behemoths crashes into a passenger car, the clear loser is the smaller vehicle.

Congress will soon consider a highway transportation bill, and there?s a good chance speed-limiting devices for semis will be part of the package. Because commercial trucking is such an integral part of the U.S. economy, this is an issue that deserves thorough debate.

July 3, 2009