Dotted line

How to read it

The MUTCD gives dotted lines two jobs. A dotted lane line warns of a change in lane function ahead, and a dotted line extension guides vehicles through an intersection, a taper area or an interchange ramp area. Its guidance is 3-foot segments with 9-foot gaps for a dotted lane line, and 2-foot segments with 2- to 6-foot gaps for an extension. An extension is the same colour as the line it extends, so a centre line continued through an intersection is a dotted yellow line: the Manual requires centre line extensions through intersections to be dotted. Oregon's manual describes three uses: before an exit ramp or intersection, where the lane will not continue on the same route; at a freeway entrance ramp, where traffic merges; and inside an intersection, to guide drivers into the proper lane.

Also searched as: dotted white line, line extension marking.

At freeway exits and entrances

The MUTCD requires a dotted white lane line between a through lane that continues past an interchange or intersection and an adjacent deceleration or acceleration lane. California's handbook calls these end of lane markings: large broken lines on a freeway or street lane that is about to exit or end, and says to look for a sign telling drivers to exit or merge. Oregon's manual says crossing a dotted line is permitted with caution.

What changed in 2023

The 2009 MUTCD gave dotted lines one function, guidance or warning of a downstream change in lane function. The 11th edition (2023) separates the two: a dotted lane line warns, and a dotted extension guides.

Look-alikes

A broken white line has longer dashes and longer gaps (10 feet and 30 feet in the MUTCD's guidance) and marks an ordinary lane line.