W20 Series — Road Work Warning Signs
Warning Signs · CA MUTCD Part 6, Chapter 6F
The W20 Series covers diamond-shaped fluorescent-orange warning signs used at the beginning of and throughout road work zones. These signs alert drivers to lane closures, road work ahead, flagger control, be-prepared-to-stop conditions, and changes in roadway geometry. The W20 Series is among the most frequently called-out sign series on California traffic control plans for utility construction, road maintenance, and public right-of-way work.
California Field Use Notes
W20 signs open the advance warning area on a TCP. Advance placement distance is calculated from the posted speed limit and roadway type. The most common plan-review deficiency is placing W20 signs too close to the activity area or omitting them on multi-approach intersections. California-specific variants (e.g., W20-1(CA), W20-7(CA)) are required on some Caltrans-jurisdiction projects.
Showing 15 of 15 signs
Warns approaching drivers that a work operation is taking place on or near the roadway ahead so they can slow down and stay alert for changing conditions.
Warns drivers that a detour is ahead and that the normal route will be interrupted, prompting them to prepare to follow an alternate path.
Warns that the road ahead is closed and that through travel will not be possible, giving drivers time to turn or follow a detour before reaching the closure.
Warns that two-way traffic will be reduced to a single shared lane ahead, where opposing directions must take turns through the work area.
Warns that a travel lane is closed ahead and that drivers in that lane will need to merge into an adjacent open lane before the work area.
Warns specifically that the right-hand travel lane is closed ahead so traffic in that lane can merge left in advance of the closure.
Warns specifically that the left-hand travel lane is closed ahead so traffic in that lane can merge right in advance of the closure.
Uses a flagger symbol to warn drivers that a flagger is controlling traffic ahead and that they must be prepared to stop or follow the flagger's directions.
The California application of the ROAD WORK AHEAD warning, reflecting CA MUTCD and Caltrans conventions for legend, size, and fluorescent orange sheeting in work zones.
The California application of the Flagger warning sign, reflecting CA MUTCD and Caltrans flagging practice, sizing, and fluorescent orange sheeting.
The W20-7a Flagger sign is a California MUTCD work zone warning sign. It is shown here as an educational reference with the official FHWA Standard Highway Signs layout and California sizing guidance.
The W20-8 Slow and Stop (on Stop/Slow Paddle) sign is a California MUTCD work zone warning sign. It is shown here as an educational reference with the official FHWA Standard Highway Signs layout and California sizing guidance.
The W20-1b Path Work (with distance) sign is a California MUTCD work zone warning sign. It is shown here as an educational reference with the official FHWA Standard Highway Signs layout and California sizing guidance.
The W20-2a Bike Detour (with distance) sign is a California MUTCD work zone warning sign. It is shown here as an educational reference with the official FHWA Standard Highway Signs layout and California sizing guidance.
The W20-3a Path Closed (with distance) sign is a California MUTCD work zone 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 W20 Series signs for a California project?
Public Ready can help you source, rent, or purchase W20 Series signs and integrate them into a compliant traffic control plan. For work zone compliance support, visit WorkZoneCompliance.com.