Headlights are required whenever poor light or bad weather keeps you from seeing people and vehicles 1,000 feet ahead. Using them then helps you see the road and helps other drivers see you.
All three situations call for a lower speed: narrow or curving roads leave little room for error, intersections and railroad crossings bring cross traffic and trains, and slick pavement makes stopping take longer. Driving slower buys you extra time to react.
When the wipers fail in rain or snow, ease off your speed at once, open the driver's window and look out of it if that is the only way to see, and then brake and leave the road at a safe spot. Wait there with your hazard flashers on until the weather clears or the wipers are fixed.
Headlights are required from half an hour after sunset until half an hour before sunrise, plus whenever rain, fog, snow, or dim light makes people and vehicles hard to see. They help you see the road and help others see you.
High speeds and heavy traffic on major highways leave little time to respond, so you need to stay focused, scan the road and mirrors continually, and be ready for hazards such as stalled vehicles, debris, or sudden slowdowns.
Each of these lowers the force of the crash: objects that give way absorb energy, a stationary object adds no speed of its own, and a glancing blow transfers less force than a head-on hit. If a collision is likely, brake hard and steer toward the least harmful option.
Passing must always be done on the paved, main part of the road. Pulling onto the shoulder or dirt edge to get by is never allowed, even next to a vehicle that is turning left.
Flashing red lights mean children are getting on or off, so you must come to a full stop at least 20 feet behind the bus. Do not move again until the lights go off and the stop arm has been pulled back in.
Fire crews need room to stop, turn, and set up their equipment, so the law bars you from trailing a fire engine answering an alarm by less than 500 feet. Riding its tail to slip through traffic is both illegal and dangerous.
Cutting across a parking lot, gas station, or other property to avoid a sign or signal is illegal. The only exception is when a police officer directs traffic that way.
A stop sign, a red signal, and a stop order from an officer directing traffic each require a full stop. The same duty applies in other cases too, such as a school bus with flashing red lights or a train approaching a railroad crossing.
Total stopping distance is the ground you cover while reacting plus the distance needed to brake, which depends on speed, brakes, tires, and the road surface. Darkness can make hazards harder to spot, but the clock itself does not change how far the vehicle needs to stop.
Tip When judging how quickly you can stop, think about speed, reaction time, brakes, tires, and pavement, not the hour.
Most states require a parallel-parked car to have its wheels within 12 inches of the curb, and some allow up to 18, so staying within 12 inches keeps you legal in either case. A wider gap leaves the car sticking out into the travel lane, where it becomes a hazard to passing traffic.
Tip A gap of roughly 6 to 12 inches keeps you within the limit while protecting your tires from the curb.
Without a sign showing otherwise, residential districts carry a 25 mph limit. Homes along the street mean children, walkers and bike riders may appear suddenly, so keep your speed down and stay ready to brake.
A siren or flashing red or blue lights mean an emergency vehicle needs the road. Move to the right edge, stop, and stay there until it has gone by; failing to do so breaks the law and puts lives at risk.
Every question in this set has its own page with the correct answer and an explanation.
