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CDL · Driving and Parking

When driving a placarded vehicle, what speed should you drive on the highway?

Reviewed by Jordan Morley, Editorial Lead at 247SimpleTests. Written by the 247SimpleTests Editorial Team from the official source material cited on every question.

Correct answer

At a speed safe for conditions, never above the posted limit, with extra caution on curves, in traffic, and during adverse weather

  1. A At the speed limit regardless of conditions
  2. B As fast as possible to minimize time on the road
  3. C Always at least 10 mph below the speed limit
  4. D At a speed safe for conditions, never above the posted limit, with extra caution on curves, in traffic, and during adverse weather

Why this is the answer

Hazmat drivers do not have a different posted speed limit than other commercial drivers, but they must drive especially defensively given the consequences of any incident. Drive at a speed safe for conditions, well below the limit when conditions are adverse (rain, snow, fog, traffic), take curves conservatively, maintain large following distances, and avoid sudden maneuvers. A passenger-vehicle crash is bad; a hazmat crash can be catastrophic. The defensive driving philosophy applies even more strictly: leave yourself enough margin that another driver's mistake or a road defect does not force you into an emergency maneuver with a placarded load.
Source: FMCSA CDL Manual 9.4.1 Defensive Driving

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About this topic: Driving and Parking

Driving and parking with hazmat covers route restrictions, railroad-crossing stops, where you may and may not park with explosives or flammables, attending the vehicle, and what to do in a fire or leak. This is one of 17 Hazardous Materials questions on driving and parking, each with a full explanation on a single study page.

New to this exam? Our CDL exam guide explains the format, scoring, and how to prepare.

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