Speed Limits and Speed Management
The Limit Is a Ceiling, Not a Target
Speed limits set the maximum lawful speed under ideal conditions. The basic speed law overrides every posted sign: you must never drive faster than is safe for the current conditions, even if that is below the posted limit. Rain, fog, night, traffic, and road work all lower the safe speed.
Posted limits vary by setting. Residential streets are typically 25 mph, school zones are often 15–25 mph when children are present, and highway limits run higher. Business districts and urban areas generally have lower limits than rural highways. Always slow down in school zones, construction zones, and neighborhoods with parked cars or children.
Speed and stopping distance are directly linked. Stopping distance = perception distance + reaction distance + braking distance. Total stopping distance rises with the square of speed: doubling speed roughly quadruples braking distance. At highway speeds, a car needs the length of a football field or more to stop.
Minimum speeds also matter. Driving too slowly in the left lane can be as dangerous as speeding; slower traffic should keep right. In work zones, fines for speeding are commonly doubled.
Traps to Watch
Examiners love to ask whether you may exceed the posted limit to pass - you may not. Another trap: assuming the posted limit is always safe in rain or fog; the basic speed law still applies. Watch for school-zone questions that hinge on whether children are present, and for questions about work zones where penalties increase. Also remember that "too fast for conditions" can be a citation even below the posted limit.
Rule of Thumb
Drive so you can stop within the distance you can see to be clear - that is your true speed limit.