Driver's License Test Prep
Texas Practice Lane Changes & Merging

The manual gives a rule of thumb for sharing the road with a tractor-trailer. It says if you cannot see the truck driver in the side mirror, what does that mean?

  1. A.
    You should flash your headlights
  2. B.
    You are in the driver's central vision
  3. C.
    You are following at a safe distance
  4. D.
    The driver cannot see you Correct
The Why

The answer is "The driver cannot see you"

The rule of thumb is: if you cannot see the truck driver in the side mirror, the driver cannot see you either. Move forward or drop back until the mirror shows the driver's face. Choice C confuses following distance with mirror visibility: a car can be well behind a rig and still sit in the trailer's rear blind spot the mirror never reaches.

Why the others miss

The traps in the wrong answers

A. You should flash your headlights

The manual does not use headlights as a blind-spot signal here. Reaches for a night-driving courtesy flash as a fix for a visibility problem the mirror rule actually addresses.

B. You are in the driver's central vision

A truck driver's central vision looks forward through the windshield, not to the rear. Applies passenger-car mirror geometry to a tractor-trailer, where the side mirror is the driver's only view to the rear.

C. You are following at a safe distance

Following distance does not decide whether the truck driver can see you. Confuses the two-second following gap with the truck-mirror rule, two separate rules from the same chapter.

The Rule

This question tests your knowledge of Lane Changes & Merging in Texas. Source: Texas Driver Manual, "Following a Truck," p.51..

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