When driving in fog, it’s best to run with your low beams on, whether day or night.

How you operate becomes more acute when the thick pea soup rolls in

For drivers it is one of nature’s worst nightmares. It can appear almost without warning. It can severely restrict your visibility and, in extreme cases, make driving nearly impossible. It can disappear in an instant or linger for days.

Fog, which occurs when warm, moist air mingles with cold air, creates havoc for truckers. For that reason, safely navigating a tractor-trailer in fog is an important maneuver taught in driver orientation classes at Freymiller Inc. “We have an area of our orientation we label ‘Driver’s Call,’ which refers to decisions made by our drivers out there that we’re not going to second guess,” says Harry Kimball, vice president of risk management at the Oklahoma City-based carrier, which received a 2009 safety award from the Truckload Carriers Association. “Any time visibility on the road is hampered, drivers are given specific instructions concerning company policy and common sense procedures.”

If the fog conditions are bad enough, shut it down, Kimball instructs drivers. “If my driver wakes up and he has visibility problems out the front of the truck, he’s going to have something worse in his rear view mirror,” he says. “My instructions are if you can’t see the nose of that Pete, and you can’t see behind you, go back to bed.”

Miguel Navarro, an owner-operator running under his own authority from Philadelphia, tries to avoid driving in fog whenever he can. “I try to divert myself from the route they give me,” he says. “Sometimes I pay a little more in fuel, but the most important thing is to get there in one piece.”

Roger Stout says to slow down gradually when you encounter fog.

Roger Stout, a Johnsrud Transport driver from Madera, Calif., is accustomed to fog from living in California’s San Joaquin Valley and tries to avoid it altogether if possible. “The best thing is not to go anywhere, but where I live it can stay that way all day,” he says.