Night Driving and Adverse Weather/Visibility Conditions
Night and reduced visibility remove your margin for error. The exam tests lighting rules, speed selection, and handling fog, rain, and snow without losing control.
Lighting rules
Headlights on from sunset to sunrise and whenever visibility is reduced by rain, fog, or snow. Dim high beams within 500 feet of oncoming traffic and within 200 feet of a vehicle you are following. Never drive faster than you can stop within the distance your headlights show; overdriving headlights is the core night hazard.
Fog and rain
Use low beams in fog, because high beams reflect off the moisture and cut your view. Slow down, track the right edge line, and never stop on the traveled portion of the road. In heavy rain, hydroplaning begins at highway speed; ease off the accelerator, avoid hard braking, and hold the wheel straight until the tires regain contact.
Wet brakes
After driving through deep water, test the brakes at low speed and dry them with light application before resuming speed.
Winter
Cut speed by at least half on snow and ice, triple the following distance, avoid cruise control, and brake and steer gently. Carry and install chains where they are required.
Worked example
You are on an unlit two-lane road at 55 mph. Low beams show about 250 feet, but stopping distance at 55 mph is roughly 300 feet. You are overdriving your lights. Slow to about 40 to 45 mph so the illuminated distance exceeds stopping distance.
Traps
Using high beams in fog; assuming flashers make a stopped bus visible enough to stay in the lane; driving the posted limit in rain; failing to dim and blinding an oncoming professional driver.