W3 Series — Intersection and Traffic Signal Warning Signs
Warning Signs · CA MUTCD Part 6, Chapter 6F
The W3 Series covers warning signs that alert drivers to stopping and signaling conditions ahead. W3-4 (BE PREPARED TO STOP) is the most common W3 sign in temporary traffic control — used ahead of flagging stations, queues, and temporary traffic signals where drivers must be ready to stop. W3-3 (STOP AHEAD) is used where a stop sign or full stop is required before reaching the work area.
California Field Use Notes
W3-4 is placed in the advance warning area upstream of a flagging station or temporary signal. It always follows the initial advance warning sign (W20-1 ROAD WORK AHEAD or W20-7 FLAGGER) and precedes the stopping point by enough distance for drivers to decelerate. In Los Angeles, it is required at all flagging stations on streets with posted speeds above 30 mph. W3-3 is used when a STOP sign controls a temporary approach created by a lane closure or crossover.
Showing 5 of 5 signs
Warns drivers that they may have to stop ahead, giving advance notice of a flagging station, queue, or signal that can require stopping.
Warns that a STOP sign or temporary stop control is ahead, giving drivers advance notice to slow down before they reach the mandatory stop.
The W3-1 Stop Ahead sign is a California MUTCD warning sign. It is shown here as an educational reference with the official FHWA Standard Highway Signs layout and California sizing guidance.
The W3-2 Yield Ahead sign is a California MUTCD warning sign. It is shown here as an educational reference with the official FHWA Standard Highway Signs layout and California sizing guidance.
The W3-5a XX MPH Speed Zone Ahead sign is a California MUTCD warning sign. It is shown here as an educational reference with the official FHWA Standard Highway Signs layout and California sizing guidance.
Educational reference only. This is not an official Caltrans, FHWA, or local agency publication and is not legal or engineering advice. Always verify sign selection, size, placement, spacing, and application against the current CA MUTCD 2026, Caltrans sign specifications, Standard Plans, project documents, and the reviewing agency’s requirements.
Need W3 Series signs for a California project?
Public Ready can help you source, rent, or purchase W3 Series signs and integrate them into a compliant traffic control plan. For work zone compliance support, visit WorkZoneCompliance.com.