Despite living in what is an official desert, Utah motorists are not unfamiliar with dense fog, often in unexpected patches along a highway. Over the years, there have been a few spectacular multivehicle pileups because of such conditions.

An experimental, fully automated fog-alert system will be installed on I-215 near where the freeway crosses the Jordan River near the west boundary of Murray. Four fog sensors will be installed. They will feed electronic signs that alert drivers about the fog and advise what speed to drive.Fog alert systems are not uncommon. Many states, including Utah, already have systems that are turned on by hand. However, they are not generally manned around the clock. The experimental system on I-215 will be the nation's first fully automated system.

When patches of fog occur on a freeway, drivers sometimes have little warning and can find themselves plunged unexpectedly into poor visibility. Previous accidents may have littered the road inside the fog with wrecked cars that become deadly obstacles.

Such a pileup in 1988 at the proposed site of the I-215 fog system damaged 68 vehicles and injured more than a dozen people.

Part of the experiment is to try to save motorists from themselves. Not everyone uses good sense and slows down in foggy conditions. Some of the danger in fog is that motorists drive at different speeds in the unsafe mist. A recommended speed flashing on a fog warning sign may alleviate some of the dangerous differences.

The Utah project is funded mostly with federal dollars. Two states - Utah and Georgia - were picked for the pilot program.

While a fog-alert system can be a lifesaver, especially if the technology works as well as hoped, there is no substitute for cautious driving when the winter weather is likely to produce smog, haze and fog.

Those conditions are most often prevalent when an inversion traps cold air in the valley. When that happens, it ought to serve as a natural warning signal that visibility is a potential problem and motorists should slow down.