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CDL · Pulling Doubles and Triples

Why are doubles and triples driven on certain routes only?

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

Length, weight, and handling characteristics make some roads unsafe; state law and federal designations specify which routes allow which combinations

  1. A Aesthetic reasons
  2. B Only on freeways
  3. C Length, weight, and handling characteristics make some roads unsafe; state law and federal designations specify which routes allow which combinations
  4. D Only on toll roads

Why this is the answer

Doubles and triples — especially LCVs — are restricted to specific routes because the combinations' length, handling, and reduced maneuverability make many roads unsafe. Restricted routes typically exclude tight urban streets, narrow rural roads, low-clearance bridges, and routes with sharp curves or steep grades. Federal regulations and state law together specify which routes allow which combinations. The National Network of highways permits standard doubles (28' + 28') with reasonable connector access; LCVs are limited to the western interstates, certain turnpikes, and approved connector routes. Driving outside the permitted route is a violation and can be dangerous.
Source: FMCSA CDL Manual 7.1.8 Routes

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About this topic: Pulling Doubles and Triples

Pulling doubles and triples means managing the most unstable combination on the road: the rear trailer whips, rolls and jackknifes more easily, following distance must grow, and the sequence of air-line and brake checks is longer. These questions cover the handling rules specific to multiple trailers. This is one of 29 Doubles and Triples questions on pulling doubles and triples, each with a full explanation on a single study page.

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