5.3 Rain, Fog, Hydroplaning & Winter Driving
Key Takeaways
Many roads are most slippery when rain first mixes with road dirt and oil, so Massachusetts drivers should slow down as soon as rain starts.
If a vehicle starts to hydroplane, the driver should ease off the gas slowly and never brake hard or turn suddenly.
In fog, use low beam headlights to reduce glare.
Bridges and overpasses freeze before the rest of the road because the ground does not insulate them.
Failing to clear ice and snow from a vehicle's roof, hood and trunk can lead to a negligent operation charge in Massachusetts.
New England weather changes fast, and the Manual devotes a full section to rain, fog and winter driving. Instructors should plan at least some wet-weather lessons so students build the habits these rules describe.
Driving in Rain or Fog
Rain and wet roads make it harder to start, stop and turn, and heavy rain, fog and mist reduce visibility. The headlight rule applies: use headlights and taillights whenever the wipers are on. Daytime running lights do not count.
Slow down as soon as rain starts
Many roads are most slippery when rain first mixes with road dirt and oil, forming a greasy film. If the road is slippery, the tires can lose traction and the car can hydroplane.
Hydroplaning
Hydroplaning happens when the tires ride on a layer of water and lose contact with the road. The Manual names three causes: road conditions, water and speed. If your vehicle starts to hydroplane, you are driving too fast.
| Do | Don't |
|---|---|
| Slowly step off the gas pedal | Hit the brakes |
| Hold your course until the tires grip again | Turn suddenly (you may lose control and skid) |
Rain and fog tips from the Manual
- Leave more space. You need more distance to stop. Be ready to stop within the distance you can see. A large truck may need twice the stopping distance of a car or motorcycle, especially on wet or icy roads.
- Beware of wet leaves. They can be as slippery as ice.
- Keep wipers and defoggers in good condition.
- In fog, use low beams to reduce glare. High beams reflect off the fog back into your eyes.
- Always use turn signals.
- If you can't see the pavement or sign posts, slow down and follow the road-edge markings.
- Avoid puddles. Wet brakes don't work properly. After driving through a large puddle, apply the brakes lightly as soon as you can to dry them until they feel normal again.
MassDOT's 511 service reports traffic, weather and construction conditions 24/7.
Winter Driving
Vehicles handle very differently on ice and snow than on warm, dry pavement, so the Manual urges drivers to practice in winter weather.
Driving technique
- Lower your speed. Drive carefully and accelerate slowly.
- Never lock the brakes on ice. Locked wheels mean lost steering control.
- If you skid, turn into the direction of the skid (section 14.2 gives the full skid procedure).
- Leave more space. Large trucks may need twice the distance to stop.
- When snow is falling, start slowly and test the brakes by tapping them gently to judge traction.
- Watch for emergency vehicles and yield to plows. Do not crowd plows.
- Bridges and overpasses freeze first. The ground does not insulate them, so they ice up before the rest of the road.
Preparing the vehicle
| Task | Why |
|---|---|
| Remove ALL ice and snow from windows, wipers, headlights, brake lights, roof, hood and trunk | Snow and ice blowing off can hit the vehicles behind you. Failing to clear it can lead to a negligent operation charge |
| Keep the gas tank at least half full | Prevents the gas line from freezing |
| Fill the washer with non-freezing fluid | Keeps the windshield clear |
| Keep wipers and the defroster in good condition | Visibility |
| Carry a blanket, flashlight and small shovel in the trunk | In case you are stranded |
| Equip the car with winter tires, an ice scraper, jumper cables and warm clothing | The Manual's winter safety kit (section 4.1) |
Note
Anyone who plows snow for compensation with a truck must have commercial plates.
Putting Weather Rules Together
| Condition | Speed | Following distance | Lights | Special rule |
|---|---|---|---|---|
| First minutes of rain | Slow down immediately | Increase | On with wipers | Oil film makes the road slickest |
| Heavy rain or standing water | Slow enough to avoid hydroplaning | Increase | On | Ease off the gas if hydroplaning; dry brakes after puddles |
| Fog | Slow; follow edge markings | Increase | Low beams | Signal every move |
| Snow or ice | Slow; gentle inputs | Increase; large trucks need twice the distance | On | Never lock brakes; turn into a skid; yield to plows |
| Bridges and overpasses | Extra caution | — | — | They freeze first |
Speed limits are set for ideal conditions. The Manual's speed section warns that driving 40 mph in a heavy rainstorm on a 50 mph highway can earn a ticket for driving too fast (section 9.1).
Coaching Wet and Winter Lessons
- Start wet-weather lessons slowly. Let the student feel how much longer it takes to stop by braking early and gently from a low speed in a safe area.
- Explain hydroplaning in words students remember: "tires on water, not on road; foot off the gas; hands steady."
- Make snow clearing part of the pre-drive check. In winter, a lesson doesn't start until the roof, hood, trunk, lights and windows are clear.
- Point out bridges. Before every bridge or overpass on a cold morning, ask the student what changes there.
A student's car starts to hydroplane on a wet highway. What does the Manual tell the driver to do?
Accelerate gently so the tires cut through the water
Slowly ease off the gas and avoid braking hard or turning suddenly
Steer sharply toward the shoulder to find drier pavement
Brake firmly to bring the tires back into contact with the road
Which headlight setting does the Manual recommend in fog?
High beams, to see as far ahead as possible
Parking lights only, to avoid blinding other drivers
Low beams, to reduce glare
No lights, so the fog does not reflect light back
A driver heads out without clearing a thick layer of snow from the car's roof. What legal risk does the Manual describe?
Nothing, because only the windshield and windows must be cleared
Only a $25 equipment warning, because snow is not a moving violation
A negligent operation charge, because snow and ice can blow into vehicles behind
An automatic 30-day suspension for unsafe equipment
Sections you finish are checked off in the contents.