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DMV Permit · Regulatory Signs

What does a white rectangular sign reading 'SPEED LIMIT 55' mean to a driver in wet weather when visibility is poor?

Correct answer

55 mph is the maximum under ideal conditions — in poor visibility or wet weather, a driver must reduce speed to what is safe and reasonable; driving at 55 in dangerous conditions can be a violation of the basic speed law even though it's at the posted limit

  1. A The driver must drive exactly 55 mph
  2. B 55 mph is the maximum under ideal conditions — in poor visibility or wet weather, a driver must reduce speed to what is safe and reasonable; driving at 55 in dangerous conditions can be a violation of the basic speed law even though it's at the posted limit
  3. C 55 mph is always the minimum speed on this road
  4. D The sign only applies during daylight hours

Why this is the answer

BASIC SPEED LAW: All states have a basic (or prima facie) speed law requiring drivers to operate at a speed that is 'reasonable and prudent' for current conditions, regardless of the posted speed limit. CONDITIONS REQUIRING REDUCED SPEED: Rain, snow, ice, or fog; Reduced visibility (dawn, dusk, curves, hills); Heavy traffic; Sharp curves; Construction zones; School or pedestrian zones; THE POSTED LIMIT is the MAXIMUM under IDEAL conditions — not the target speed in all conditions. LEGAL EXAMPLE: Driving 55 mph in dense fog or on black ice can be cited as driving too fast for conditions even though you're at or below the posted limit. This principle is tested directly on permit exams because many new drivers believe posted limits are always 'safe.'
Source: DMV Road Signs — Speed Limit Signs and Basic Speed Law

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