Driver's License Test Prep
US Road Signs Road Markings

Two parallel solid white lines separate lanes traveling in the same direction. What do they require of a driver in one of those lanes?

Two parallel solid white lines running lengthwise down a dark roadway.
  1. A.
    Remain in your current lane and do not cross the marking. Correct
  2. B.
    Change lanes only when a driver behind you signals to pass.
  3. C.
    Yield to the adjacent lane, then merge across when it is clear.
  4. D.
    Cross only to enter or exit a carpool lane on the left.
The Why

The answer is "Remain in your current lane and do not cross the marking."

Two solid white lines forbid lane changes, so you stay in your current lane until the marking becomes a broken or single line. The trap is the carpool-lane answer: this pattern often runs along the edge of an HOV or managed lane, and a driver eligible for that lane assumes eligibility lets them slip across the paint. The line itself is the barrier, and entry to the HOV lane happens only where the marking changes.

Why the others miss

The traps in the wrong answers

B. Change lanes only when a driver behind you signals to pass.

A signal from a following driver does not unlock a marking that prohibits the crossing in the first place. This answer reads the double white as a courtesy passing rule that yields to whoever wants past from behind.

C. Yield to the adjacent lane, then merge across when it is clear.

The double white is not a merge invitation; the crossing itself is prohibited, so checking traffic does not authorize it. This answer handles the marking the way a driver handles a dashed line, treating it as a merge that clears with a look and a gap.

D. Cross only to enter or exit a carpool lane on the left.

The double white running along an HOV or managed lane is the barrier itself; entry and exit happen where the paint changes to a broken or single line. This answer assumes a carpool driver's eligibility for the HOV lane also unlocks the marking that walls it off.

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 (Double Solid White Lane Line)..

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