CDL · Driving Combination Vehicles

When making a right turn with a combination vehicle, why must the driver avoid swinging wide to the left before turning?

Correct answer

Swinging left first can mislead following drivers into thinking you're changing lanes or turning left, and a vehicle may try to pass on the right and be caught between your trailer and the curb as you turn — instead, turn wide as you complete the turn, keeping the rear close to the curb on approach

  1. A Swinging left first can mislead following drivers into thinking you're changing lanes or turning left, and a vehicle may try to pass on the right and be caught between your trailer and the curb as you turn — instead, turn wide as you complete the turn, keeping the rear close to the curb on approach
  2. B It wastes fuel
  3. C It damages the tires
  4. D It is illegal in all states

Why this is the answer

RIGHT TURNS WITH COMBINATION VEHICLES — OFF-TRACKING: Because the trailer wheels track INSIDE the tractor's path (off-tracking), drivers need extra room for right turns.

Correct technique: Turn wide as you COMPLETE the turn (swing out as you go through/finish the turn), keeping the rear of the vehicle close to the curb on the approach; this prevents the trailer from cutting over the curb or hitting objects/vehicles to the right; AVOID swinging wide to the LEFT before starting the turn because: it misleads following drivers (looks like a lane change or left turn); a driver may attempt to pass you on the RIGHT; when you then turn right, that vehicle is trapped between your trailer and the curb — a 'squeeze' that causes serious accidents.

Instead: keep the rear close to the curb on approach; if you must swing wide, do it as you complete the turn while watching your mirrors; block the right lane if necessary rather than inviting a pass on the right; off-tracking and proper turning are key combination vehicle skills tested on the exam and in the road test.

Source: FMCSA CDL Manual — Combination Turns, Off-Tracking

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About this topic: Driving Combination Vehicles

Off-tracking, jackknife risk, and rearward amplification mean a tractor-trailer behaves nothing like a single vehicle. Smooth inputs and conservative speed prevent the worst outcomes. This is one of 20 Combination Vehicles questions on driving combination vehicles, each with a full explanation on a single study page.

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