Massachusetts · Handbook chapter 4 · 5 min read

Following distances, reaction and stopping distances, when Massachusetts law requires headlights, high beams, night and drowsy driving, rain, fog, hydroplaning and winter driving.

Why this chapter matters

Most crashes come down to too little space and too little time. Massachusetts gives you firm numbers to work with: the three-second rule, four seconds behind a motorcycle, headlights half an hour after sunset, and dimming within 500 feet.

The defensive habit

• Look well ahead and around you, and check your mirrors often.
• Expect other drivers, pedestrians and bicyclists to make mistakes or ignore signals.
• Watch for back-up lights, people getting out of parked cars and children near playgrounds, schoolyards and shopping centers.
• Remember that others may not hear you: about one in five people of driving age is Deaf or hard of hearing.
• Right-of-way is something you give. Giving it up to prevent a crash is part of defensive driving.

Never drive after drinking, after taking medicine that causes drowsiness, when very tired, or when angry or upset.

Space around your vehicle

Count the seconds from the moment the vehicle ahead passes a fixed object. If you reach the object before you finish counting, you are too close. Three seconds is a minimum; add more in rain, snow or ice, near blind driveways, and near children or cars backing out.

• Tailgating is illegal and is the main cause of rear-end crashes. The fine can reach $100.
• If someone tailgates you, change lanes or pull aside and let them by.
• Never cut in front of heavy equipment or a tractor-trailer, which needs far more room to stop.

Reaction and stopping distance

It takes about three-quarters of a second to see a hazard and get your foot on the brake. On dry, level pavement:

Stopping takes longer downhill, on wet or uneven roads and in heavier vehicles. A large truck can need twice the distance of a car.

Braking tips

• Brake early and gently.
• Do not rest your foot on the brake ("riding the brakes").
• With antilock brakes, never pump the pedal.
• Slow down before curves and wherever you cannot see clearly ahead.

Horn, headlights and hazard lights

Use the horn to warn people and avoid crashes, never to vent anger, hurry a slow driver or move a traffic jam.

You must use headlights:

• From half an hour after sunset to half an hour before sunrise.
• When you cannot clearly see people or vehicles 500 feet ahead.
• Whenever your windshield wipers are on. Daytime running lights are not enough.
• In rain, snow or fog, and when driving through a tunnel.

If you break down, move as far off the road as possible, turn on your hazard lights and stay off the road. Never change a tire in a traffic lane.

Night driving

• Drive more slowly and keep a speed that lets you stop within the distance you can see.
• Set the inside mirror to "night" and keep interior lights off.
• Do not look into oncoming headlights. Look toward the lower right side of your lane.
• High beams show about 350 feet ahead; low beams about 100 feet.
• Dim your high beams within 500 feet of an oncoming vehicle and within 200 feet of a vehicle you are following.
• If an oncoming driver keeps high beams on after you flick your lights, keep right and do not answer with your own high beams.

Drowsy driving

Drowsy crashes happen most often between midnight and 6 a.m. or in the late afternoon, usually one driver alone running off a rural road at speed. The only real cure is sleep. Coffee or a short nap helps only briefly. Drifting over lines or hitting rumble strips are warning signs.

Rain and fog

• Slow down as soon as rain begins. Roads are often slickest when rain first falls, mixing with oil and dirt.
• Hydroplaning means your tires are riding on water. Ease off the gas; do not brake hard or turn suddenly.
• Wet leaves can be as slippery as ice.
• In fog, use low beams.
• After driving through a deep puddle, brake lightly to dry the brakes.

Winter driving

• Slow down, accelerate gently and leave more space.
• Never lock the brakes on ice. If you skid, steer in the direction of the skid.
• Bridges and overpasses freeze first.
• Give snowplows room and do not crowd them.
• Clear all snow and ice from windows, lights, the roof, hood and trunk before you drive. Snow flying off your car can lead to a negligent operation charge.
• Keep the gas tank at least half full.