Driver's License Test Prep
US Road Signs Road Markings

Two lanes of same-direction traffic are separated by a solid white line. What does this marking tell drivers?

A single solid white line running lengthwise down a dark roadway.
  1. A.
    Lane changes through the marked area are discouraged. Correct
  2. B.
    The marking is an absolute prohibition on crossing under any circumstances.
  3. C.
    Traffic on the other side of the line moves in the opposite direction.
  4. D.
    Vehicles may pass slower traffic whenever the road ahead is clear.
The Why

The answer is "Lane changes through the marked area are discouraged."

A solid white line between same-direction lanes discourages lane changes through the marked area, so drivers should hold their lane through the solid section and cross only when necessary. The "absolute prohibition" answer traps drivers who confuse a solid white lane line with a solid yellow centerline, reading any solid line as an unconditional ban rather than as the passing or lane-change restriction it actually marks.

Why the others miss

The traps in the wrong answers

B. The marking is an absolute prohibition on crossing under any circumstances.

The marking discourages lane changes and allows crossing when necessary; it does not function as an unconditional ban. Confuses a solid white lane line with the solid yellow centerlines that restrict passing across opposing traffic.

C. Traffic on the other side of the line moves in the opposite direction.

Same-direction traffic runs on both sides of a solid white line; yellow lines mark the boundary against oncoming traffic. Treats every solid lane line as a division between opposing flows, ignoring that line color is what carries the direction cue.

D. Vehicles may pass slower traffic whenever the road ahead is clear.

The solid white line governs staying in the lane, not a general permission to pass based on the view ahead. Carries the passing habit learned on rural centerlines onto a marking that speaks to lane discipline instead.

The Rule

This question tests your knowledge of Road Markings on the roads of every US state . Source: Manual on Uniform Traffic Control Devices, marking 3B.04 (Solid White Lane Line)..

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