10.1 Driving in Uncertain Weather

10.1 Driving in Uncertain Weather

Quick Answer: Always clear your windows before driving in winter. Ice can cause a vehicle to lose traction. Snow mixed with significant wind cuts visibility; watch drifting snow in rural areas, where only a few inches can make roads impassable. Watch ice especially at intersections, and use headlights to be seen. Moisture on ramps, bridges, and overpasses may freeze first. Stay a safe distance behind snowplows. Warm the engine in very cold weather. Drive with a full tank so the heater can stay on if you are stranded. Brush snow off headlights and taillights. Carry a winter survival kit: sand or carpet strips, booster cables, blankets, shovel, flashlight, extra clothing, candles, matches, nonperishable snack food, and bottled water. Wet roads are especially slick immediately after rainfall — you ride a thin layer of oil, dirt, and water that leads to hydroplaning, which increases with speed and can leave no friction to brake, speed up, or turn. Do not drive on bald or badly worn tires. Slow in heavy rain, standing water, or slush. After puddles, pump the brakes to dry them. If water is deeper than the treads, slow down. Use headlights to be seen. In fog, use low beams (not high beams) plus flashing emergency signals; if visibility is near zero, pull off as far as possible and stop. High winds hit high-profile vans and SUVs hardest. Flash flooding causes more deaths than any other roadway weather event each year. Do not drive around barricades or Road Closed signs, do not drive where water is over the road, and abandon a stalled car as soon as possible.

Uncertain weather sits in Indiana Driver's Manual Chapter 7 (Safe Vehicle Operation). The knowledge exam's traffic maneuvers and rules component draws from Chapters 6, 7, and 8. These are not courtesy tips. The exam will swap high beams for low beams in fog, treat a flooded street as "driveable if you know it," and ask whether you stay in a stalled car. Memorize the manual's duties, not a weather app's advice.

Winter: ice, snow, cold, and being seen

Winter weather presents dangers from ice, snow, and very cold temperatures. Always clear your windows before driving. A fist-sized hole in a snow-covered windshield is not a cleared window. Ice on the roadway is a potentially dangerous condition that can cause a vehicle to lose traction.

Snow, especially when mixed with significant wind, poses several problems. Visibility may be substantially reduced. Watch for drifting snow, particularly in rural areas, where only a few inches of snow can cause roads to become impassable. Always watch for icy conditions when there is snowfall on the ground, particularly at intersections, and use your headlights to be seen by other drivers. Being seen is the winter lighting rule, not a hint that you may skip lights in daytime snow.

Moisture on ramps, bridges, and overpasses may occasionally freeze before other sections of the driving roadway. The lane you just left can look wet-and-black while the structure ahead is already ice. Stay a safe distance behind snowplows. Do not ride the plow's spray for a "cleared" track. The blade, the windrow, and the sudden change from packed snow to bare pavement are all crash setups.

Always allow the engine plenty of time to warm up before driving in very cold conditions. Drive with a full tank of gas so that if you are stranded, the heater can remain in use for as long as possible. Brush the snow off your headlights and taillights frequently. A buried lamp does not count as using headlights to be seen.

Consider carrying a winter survival kit in the vehicle:

• Sand or strips of carpet for traction
• Booster cables
• Blankets
• Shovel
• Flashlight
• Extra clothing
• Candles and matches
• Nonperishable snack food
• Bottled water

The kit is for being stranded. The full tank is what keeps the heater running while you wait.

Rain and hydroplaning

Wet roadway surfaces can be dangerously slick, especially immediately following a rainfall. When you drive on wet roads, the vehicle is actually traveling on a thin layer of oil, dirt, and water, which can lead to hydroplaning.

Hydroplaning increases with speed. At any point your tires may be in contact only with the oil, dirt, and water. If that happens, there is no friction to brake, speed up, or turn, and a gust of wind, a change of road level, or a slight turn can cause you to lose control.

• Do not drive on bald or badly worn tires.
• Slow down when there is heavy rain, standing water, or slush on the road.
• After driving through water puddles, test your brakes by pumping them. Doing so helps to dry them.
• If the water is deeper than your tire treads, slow down.
• Use your headlights to be seen by other drivers.

The exam trap is thinking hydroplaning needs a flooded street. The manual's first rain after a dry spell is the slickest because oil and dirt have not yet washed off. Another trap is slamming the brakes after a puddle instead of pumping them to dry. Headlights in rain are for being seen, including in daylight rain.

Fog: low beams, flashers, and when to stop

Fog can greatly reduce your visibility of other vehicles, pedestrians, and traffic signals. Drive cautiously and at reduced speeds.

Do not use high headlight beams. Low headlight beams better illuminate the road and objects ahead. High beams bounce off the water droplets and wash out what you need to see.

Headlights and flashing emergency signals should be used while driving in fog.

If fog closes in completely, and visibility is reduced to near zero, carefully pull off the road as far as possible and stop. Do not sit in a travel lane with lights on "so people can find you." Pull as far as possible, then stop. Flashers and headlights belong with driving in fog; the full stop belongs with near-zero visibility.

High winds

Strong winds have a significant effect on high-profile vehicles (for example, vans and sport utility vehicles). Be aware of such conditions and take appropriate action for your safety. A crosswind on an open interstate or a river bridge will push a van or SUV farther than a low sedan. Slow down, keep both hands on the wheel, and expect a shove when you pass a truck or leave a cut.

Flash flooding: the deadliest roadway weather event

Flash flooding causes more deaths than any other roadway weather event each year. Be especially alert at night or when driving on unfamiliar roads.

If you are caught in a storm or come upon a hazardous situation, follow these rules:

• Do not drive around traffic barricades or past road closed signs.
• Watch for bridges, culverts, and roadbeds that may be washed away or undermined by floodwaters.
• Do not drive where water is over the road, because the depth of the water is not always obvious, and the water may hide washouts.
• If your car stalls in a flooded area, abandon it as soon as possible, because flood waters can rise rapidly and sweep a car and its occupants away.

"I can see the centerline" is not a depth gauge. "I will wait it out in the car" is the opposite of the manual: abandon as soon as possible. Barricades are not optional. Driving around them is how people enter a washout that used to be a road.

Indiana scenarios

First rain on I-65. After a dry week, a shower starts. The pavement is especially slick immediately following the rainfall. You slow down, keep headlights on to be seen, and treat the oil-dirt-water film as hydroplaning risk, not "just wet."

Rural drift. A few inches and wind on a county road hide the lane. Drifting snow can make that road impassable. You do not hug a snowplow's bumper; you stay a safe distance behind.

Morning overpass. The arterial looks wet. The ramp, bridge, or overpass may already be ice. You treat those structures as the first to freeze, especially at intersections.

US 31 fog. You use low beams and flashing emergency signals. High beams stay off. If the fog drops to near zero, you pull off as far as possible and stop.

Night flood on an unfamiliar road. Water is over the road. You do not drive through it or around the Road Closed barricade. If the car stalls, you get out immediately — flood water can rise rapidly and sweep the car and occupants away.

Crosswind SUV. A van or SUV on an open interstate feels the high-profile push. You slow down instead of correcting with big steering inputs.

Exam traps

• Using high beams in fog (low beams illuminate the road and objects ahead).
• Skipping emergency flashers while driving in fog, or failing to pull off as far as possible when visibility is near zero.
• Treating hydroplaning as a deep-water-only event; it starts with the oil, dirt, and water film immediately after rainfall and increases with speed.
• Staying in a stalled car in a flooded area instead of abandoning it as soon as possible.
• Driving around barricades or past Road Closed signs, or assuming water over the road is shallow because you "know that street."
• Following a snowplow closely, or leaving snow on windows, headlights, or taillights.
• Assuming a dry-looking lane means the bridge or overpass is not ice.
• Driving on bald tires in rain, or forgetting to pump the brakes after puddles to dry them.

Clear the glass, turn on lights to be seen, use low beams in fog, never enter floodwater, and abandon a stalled car in a flood.