Clear need for response to fatal fog

Rushing through zero-visibility fog at 70 miles per hour is about as risky as closing your eyes on the freeway for kicks.

It amounts to a death wish, but it is what thousands of motorists do every year when they encounter fog. The result: horrific crashes that are by far the most deadly events that occur on the highway.

The problem was illustrated this month when 30 cars ended up in a pile of twisted and burnt wreckage in a dense fog along Interstate 43 in Wisconsin. Rescue workers pulled 10 bodies from the wrecks and three dozen people were injured in the worst crash in the state’s history.

After a day of digging through the wreckage, state troopers, already stunned by the horror of the scene, found an additional six cars they hadn’t known about.

Road-obscuring fog occurs throughout the country, but it is particularly deadly in California’s Central Valley. Earlier this year, 77 vehicles rammed into one another on California 58 about 90 miles north of Los Angeles. Luckily, only one person was killed.

And a dust storm north of Coalinga in November 1991 caused a 104-vehicle pileup that left 17 dead and 151 injured. Because visibility conditions are similar in fog and dust storms, the California Highway Patrol created a special fog committee after the accident.

Southern California is not immune. Last year, 14 accidents that involved 43 cars and trucks occurred in dense fog along Interstate 215 in Perris. Nearly a dozen people were hospitalized.

It is not clear why people badly misjudge the dangers of driving in fog. Despite the human toll, it has received little study at the national level. The two federal agencies that deal with auto and highway safety say they have not studied the problem and do not consider it within their areas of interest.

The National Highway Traffic Safety Administration, in fact, referred questions to the Federal Highway Administration, while officials at that agency said it was the responsibility of NHTSA.

The only government agencies that seem to be doing any thinking about the problem are state highway patrols.

Is fog on the highways a big problem? You bet.

An examination of the Fatality Analysis Reporting System, the database of all fatal accidents in this country, shows that foggy conditions were cited by police in 1,387 highway deaths in 2001.

The deaths occurred in 548 crashes, meaning that more than two people died, on average, in every crash. That tells you these are violent, high-speed impacts.

The question is, can anything be done to prevent such crashes?

The California Highway Patrol, which frequently deals with fog-related accidents, says drivers misjudge speed and stopping distances in fog, according to Sgt. Ted Eichman, chairman of the CHP’s Central Valley Fog Committee. “It isn’t the fog that causes the accidents. It’s the speed,” Eichman said.

In mild fog, for example, visibility can be reduced to 100 feet, but people often drive at 55 mph, which is too fast to respond to something blocking the road ahead.

At 55 mph, the typical motorist needs 121 feet -- a distance covered in slightly more than a second -- to perceive a threat and hit the brake pedal, and 144 feet more to come to a stop. The total of 265 feet is more than twice the 100 feet of visibility, meaning that the car would crash into an obstacle at a fairly high speed of perhaps more than 30 mph.

But what breakdown in judgment occurs in fog?

Very seldom does alcohol play a role in these crashes. Wisconsin troopers told The Times they did not believe that any of the motorists involved in the crash this month were alcohol-impaired.

Research from the University of Wales indicates that drivers tend to underestimate their true speed and go faster the foggier it gets. When asked in laboratory experiments to drive at 112 kilometers per hour, subjects actually drove at 150 kph in fog, 140 kph in misty conditions and 130 in clear conditions.

One theory is that people have difficulty judging movement when there is low contrast, typical of fog.

But nobody is going to re-engineer the human vision system. Solutions must be found elsewhere.

After the 1991 California crash, the CHP began a program to lead convoys of vehicles through fog.

In some cases, the CHP shuts down affected interstates altogether, though the drawback is that traffic is routed onto equally foggy country roads that can be even more deadly.

Tennessee began looking into more active accident prevention systems after a 1990 chain-reaction collision involving 99 vehicles. It put a fog detection and warning system along Interstate 75. A central computer is fed data from fog detectors and vehicle speed detectors. It can alert state traffic managers when fog and vehicle speeds are reaching lethal levels, allowing the activation of roadside warning signs and the use of highway patrols to slow traffic.

But I wonder why the intelligence can’t be put on-board the vehicle.

A visibility sensor on the front end of a car could tie into the main control module for the engine, which already knows the car’s speed. A simple program could determine if a car is going too fast for a given visibility condition. If that’s the case, a warning could be sounded. It might be an annoyance, but it would be making calculations that few drivers are capable of doing by the seat of their pants. It might even be worth considering allowing such a system to automatically slow the engine.

Visibility sensor systems already are used to activate headlights, reducing the number of vehicles traveling at dusk with their lights off. The systems do not allow drivers to turn off the headlights in the dark.

If federal officials cared about this problem a bit more, maybe all the weight of prevention would not be falling on the highway patrols across the country.

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Ralph Vartabedian cannot answer mail personally but responds in this column to automotive questions of general interest. Write to Your Wheels, Business Section, Los Angeles Times, 202 W. 1st St., Los Angeles, CA , 90012.

E-mail: ralph.vartabedian@latimes.com.