4.1 Reduced Visibility, Headlight Rules & Night Driving

What Reduced Visibility Means

Visibility is your ability to clearly see everything around you on the road: other vehicles, pedestrians, signs, signals and pavement markings. The most common causes of reduced visibility are darkness, fog, heavy rain and snow. Driving in these conditions takes more concentration and preparation than normal driving.

When visibility is low, the manual gives two lane-keeping guides:

• Use the lines on the edge of the road, or the right side of the road, as a guide.
• Yellow markings should never be on your right; they divide opposing traffic and mark the left edge. White markings mark the right edge and divide same-direction lanes.

When Headlights Are Required

Nighttime, fog and stormy weather are the most important times to use headlights. Headlights help you see, and they help oncoming drivers see you. The wipers-on, lights-on violation is not a moving violation, so it carries no points, but it is still against the law. Many cars have daytime running lights that do not turn on the taillights. Switch the headlights fully on in bad weather so drivers behind you can see you.

Low Beams Versus High Beams

Use low beams when:

• Driving in normal situations, such as at night on a road with streetlights.
• Driving in fog, rain or snow. High beams reflect off water droplets and snowflakes and create glare.
• Entering a tunnel or a construction area. The law does not always require it, but it helps other drivers and workers see you.

Use high beams on roads without streetlights so you can see other vehicles and people. You must switch to low beams:

Driving at Night

The manual calls night driving riskier and more difficult than daytime driving. It is harder to judge how far away other vehicles are and how fast they are moving, and you can see only as far as your headlights reach. The manual's suggestions:

• Use your headlights and follow the high-beam rules above.
• Do not stare into oncoming headlights. Look at the road in front of you or slightly to the right, at the right edge of your lane or of the road.
• Increase your following distance so you can stop if the vehicle ahead stops quickly.

Other good night habits:

• Do not outdrive your headlights. If you cannot stop within the distance your headlights light up, you are going too fast for conditions.
• Keep the windshield, headlights and mirrors clean; dirt and film multiply glare.
• Watch for dim reflective objects. The manual warns that a faint reflection at night could be a bicycle in the travel lane, not something off the road. Use low beams when approaching a bicyclist.
• Watch for pedestrians in dark clothing near crosswalks, bus stops and parked cars.
• Fatigue is worse at night. If you feel drowsy, stop and rest (see Section 5.4).

Sharing the Road at Night

• When following a vehicle at night, stay on low beams once you are within 300 feet, so your lights do not glare in its mirrors.
• When an oncoming driver forgets to dim, do not retaliate with your own high beams. Look toward the right edge line and slow down until the vehicle passes.
• On rural Maryland roads, deer are most active around dawn and dusk. Slow down where Deer Crossing signs are posted, and use high beams when no one is ahead of you.

Why Night Driving Raises Risk

Your eyes need time to adjust after glare, and many hazards, including pedestrians, animals and unlit bicycles, do not light themselves up. Combine darkness with rain, a curvy road or fatigue and the risks multiply. That is why Maryland requires 10 of the 60 practice hours for new drivers under 25 to fall in the period from 30 minutes before sunset to 30 minutes after sunrise.

Scenario Practice

1. Dusk, light rain, wipers on continuously. Headlights must be on now, both because you are using your wipers and because visibility is dropping.
2. Dark two-lane road, high beams on, a car appears about a quarter mile ahead coming toward you. Switch to low beams before you are 500 feet apart.
3. Following a car on an unlit highway, 250 feet behind. You should already be on low beams.
4. Driving into a construction zone at night. Use low beams so workers and drivers can see you without glare.