Driver's License Test Prep
US Road Signs Road Markings

A lane line becomes a series of closely spaced short white dots through an interchange. What does this dotted pattern tell you about the lane?

A row of small evenly spaced white square dots running lengthwise down a dark roadway.
  1. A.
    The lane ends at the next intersection and you must change lanes now.
  2. B.
    The lane continues but is shared, dropping, or merging. Correct
  3. C.
    The lane is reserved for buses or high-occupancy vehicles through the gap.
  4. D.
    You may cross the dotted line only in an emergency.
The Why

The answer is "The lane continues but is shared, dropping, or merging."

A dotted white extension line is a lane line continued in short, closely spaced dots through a merge, exit, interchange, or intersection area. The dots tell you the lane keeps going, but its purpose is changing: it is shared with entering traffic, about to drop, or being merged into another lane. Track the dots to stay aligned and watch for cars entering or exiting through the gap. The trap is the answer that reads a broken-up line as a lane-drop warning. A driver who learned that a solid line becomes broken when a lane is ending carries that habit forward and reads any interruption in the striping the same way. The dotted extension does the opposite: it says the lane continues where the normal stripe cannot be drawn, and only the pattern of use is changing.

Why the others miss

The traps in the wrong answers

A. The lane ends at the next intersection and you must change lanes now.

The dotted pattern does not announce a lane ending; it marks a continuation through a gap in the normal striping. This answer reads any break in a lane line as an end-of-lane warning that demands an immediate lane change.

C. The lane is reserved for buses or high-occupancy vehicles through the gap.

Dotted white extension lines guide alignment across a merge or interchange; they do not designate an HOV or bus-only lane. This answer confuses the dotted extension with diamond symbols and solid markings that identify HOV or bus-only lanes.

D. You may cross the dotted line only in an emergency.

The dotted extension is a guidance marking through gaps in normal striping, not a barrier line with an emergency-only crossing rule. This answer applies the solid-white-line crossing restriction to a marking whose whole purpose is guiding movement across a striping gap.

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 (Dotted White Extension Line)..

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