Winter driving for trucks and cars

Prepare before the weather turns

Winter driving starts in the yard or driveway. A well-prepared vehicle and driver avoid most problems.

Driving on snow and ice

• Slow down. Commercial driver training commonly advises cutting speed by about a third on wet roads, by half or more on packed snow, and slowing to a crawl on ice.
• Increase following distance dramatically; see stopping distances.
• Be smooth. Accelerate, brake and steer gently. Sudden inputs cause skids.
• Watch for black ice, a thin clear layer that looks like wet pavement. It often forms at dawn, in shaded areas and on bridges and overpasses, which freeze before the road surface.
• Watch the spray from other vehicles. If it suddenly stops, the road surface may be freezing.
• Avoid cruise control on slippery roads.
• Turn off the engine brake or use it cautiously on slippery roads, because it can lock the drive wheels; see jake brakes.

Skids and jackknifes

A skid happens when tires lose grip. In a car, if the rear slides, look and steer gently where you want to go and ease off the pedals. Modern stability control systems help, but they cannot overcome physics.

A jackknife occurs when a tractor's drive wheels or the trailer's wheels lose traction and the trailer swings around toward the cab. Causes include braking too hard, especially on curves, accelerating too hard on slippery roads, and an empty or lightly loaded trailer. Prevention is about speed, smooth braking and space.

Tire chains and traction laws

Several mountain states have chain or traction laws for commercial vehicles during winter storms. For example, Colorado enforces chain requirements for commercial vehicles on I-70 in the mountains, and California posts chain controls on mountain highways. Requirements change by state, road and conditions.

Tips for chains:

• Practice fitting them in good weather.
• Carry the right size and number for your vehicle and state rules.
• Pull completely off the road at designated chain-up areas.
• Drive slowly with chains, usually no faster than about 30 mph or the speed the manufacturer specifies.

When to stop

Pressure to deliver on time never outweighs safety. Signs that it is time to park:

• Visibility drops so low you cannot see the road edge
• Vehicles are sliding off the road ahead
• Your vehicle is losing traction even at low speed
• Roads are officially closed or chain controls are beyond your equipment

Find a safe, legal place to park, such as a truck stop or rest area, never the highway shoulder unless you have no choice. Call your dispatcher or let someone know where you are.