Warning Signs
Diamond-shaped signs that alert drivers to changing conditions ahead, including work zones, flaggers, lane reductions, and merging traffic.
Warning signs give road users advance notice of conditions that may not be obvious, so they can slow down and react safely. In temporary traffic control, warning signs are diamond-shaped with a fluorescent orange background and black legend or symbol, and they make up most of the advance warning area on a California TCP.
The W-series signs below cover the most common work-zone warnings in California: ROAD WORK AHEAD, the lane- and shoulder-closure series, FLAGGER, WORKERS, BE PREPARED TO STOP, and the lane-reduction signs. Correct advance distance for the posted speed is one of the most common plan-review issues with these signs.
Sizes follow the CA MUTCD — typically 48″ × 48″ on conventional roads and 60″ × 60″ on expressways and freeways — but local agencies may require larger signs based on the roadway classification and conditions.
Browse by Series
Select a series to see all signs in that group with downloads and field-use notes.
W20 Series
The W20 Series covers diamond-shaped fluorescent-orange warning signs used at the beginning of and throughout road work zones.
W21 Series
The W21 Series includes warning signs that alert drivers to workers, equipment operators, and utility crews in or near the traveled way.
W3 Series
The W3 Series covers warning signs that alert drivers to stopping and signaling conditions ahead.
W4 Series
The W4 Series covers warning signs for merging lanes, added lanes, and lane-change conditions.
W9 Series
The W9 Series includes warning signs for lane-ending and divided-highway transitions.
OM Series
The OM Series covers object markers — retroreflective warning devices used to delineate physical obstructions in or adjacent to the traveled way.
All Warning Signs
Showing 62 of 62 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.
Uses a worker symbol to warn that workers are present on or near the roadway ahead, signaling drivers to reduce speed and increase caution.
Warns that work is taking place on the shoulder ahead, alerting drivers to workers and equipment near the edge of the traveled way.
Warns that the shoulder is closed ahead and is not available for stopping, disabled vehicles, or travel through the work area.
Warns that utility work is taking place on or near the roadway ahead, alerting drivers to utility crews, equipment, and possible lane or shoulder impacts.
Warns drivers that they may have to stop ahead, giving advance notice of a flagging station, queue, or signal that can require stopping.
Uses a symbol to warn that a travel lane is ending and that traffic must merge in the indicated direction where the roadway narrows.
A word-message warning that a travel lane is ending ahead, telling drivers the number of through lanes will be reduced.
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.
Warns that a STOP sign or temporary stop control is ahead, giving drivers advance notice to slow down before they reach the mandatory stop.
Uses a symbol to warn that two lanes of traffic are merging into one, alerting drivers in both lanes to yield and merge safely.
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.
The W21-1a Workers 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 W21-2 Fresh Oil 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 W21-3 Road Machinery Ahead 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 W21-4 Slow Moving Vehicle 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 W21-5b Shoulder 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.
The W21-6 Survey Crew 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 W21-8 Mowing Ahead 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 W22-1 Blasting Zone Ahead 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 W22-3 End Blasting Zone 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 W23-1 Slow Traffic Ahead 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 W24-1 Double Reverse Curve (1 lane) 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 W24-1a Double Reverse Curve (2 lanes) 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 W24-1b Double Reverse Curve (3 lanes) 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 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.
The W5-1 Road Narrows 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 W5-2 Narrow Bridge 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 W5-3 One Lane Bridge 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 W6-1 Divided Highway 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 W6-2 Divided Highway Ends 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 W6-3 Two-Way Traffic 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 W7-1 Hill 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 W8-1 Bump 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 W8-2 Dip 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 W8-3 Pavement Ends 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 W8-5 Slippery When Wet 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 W9-1 Right (Left) Lane Ends 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 W9-3 Interior Lane Shift 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 W11-1 Bicycle 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 W11-2 Pedestrian 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 W11-8 Emergency Vehicle 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 W11-9 Handicapped 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 W12-1 Double Arrow 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 W13-2 Advisory Exit Speed 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 W17-1 Speed Hump 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 W23-2 New Traffic Pattern Ahead 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 W26-1 W26-1 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.
Official Sources (external)
This is an educational reference. Verify sign use, size, placement, and application against the current CA MUTCD, Caltrans sign specifications, Standard Plans, and the reviewing agency. Official source links are gathered in one place.
View official sourcesEducational 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.
Frequently Asked Questions
Why are work-zone warning signs orange instead of yellow?
Permanent warning signs use a yellow background, but in a temporary traffic control zone the same warnings are shown on a fluorescent orange background to distinguish work-zone conditions. The shape (diamond) and black legend stay the same.
What size is a ROAD WORK AHEAD sign in California?
The CA MUTCD minimum is typically 48″ × 48″ on conventional roads and 60″ × 60″ on expressways and freeways. The correct size depends on the roadway classification — confirm against the CA MUTCD and the reviewing agency.
Is the W20-7 Flagger sign a symbol or a word message?
W20-7 is the flagger symbol sign (a flagger figure). A separate word-message version exists, but the symbol sign is the standard advance warning placed ahead of a flagging station, usually with BE PREPARED TO STOP.
Which warning signs are used for a lane closure?
Lane closures commonly use the W20-5 series (LANE CLOSED AHEAD, RIGHT/LEFT LANE CLOSED AHEAD) for the advance warning, with W4-2 (lane-ends merge symbol) or W9-2 (LANE ENDS) reinforcing the merge at the taper.
Need warning signs for a California work zone?
Public Ready can help you rent or purchase the orange warning signs used in California temporary traffic control and fit them to your TCP.
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