Although officially a temporary traffic control sign in the MUTCD, municipalities in CA have long used this sign for permanent applications.

MUTCD standards for this sign:

The THRU TRAFFIC MERGE LEFT (RIGHT) (W4-7) sign should be used in advance of an intersection where one or more lane closures on the far side of a multi-lane intersection require through vehicular traffic on the approach to the intersection to use the left (right) lane to proceed through the intersection.

Standard Sizes

48" x 48"

36" x 36"

30" x 30"

Note:

Also available as W4-7(RT) THRU TRAFFIC MERGE RIGHT

Popular Construction-Regulatory-Warning Signage > Warning Signs > W1-1(LT) HORIZONTAL ALIGNMENT TURN SYMBOL (LEFT)