W20-2 Detour Ahead Sign
Warns drivers that a detour is ahead and that the normal route will be interrupted, prompting them to prepare to follow an alternate path.
| Sign code | W20-2 |
|---|---|
| Federal code | W20-2 |
| Name | Detour Ahead |
| Category | Warning Signs |
| Shape | Diamond |
| Color | Orange background, black legend |
| California status | Used in California per CA MUTCD |
| Typical CA minimum size | 48" × 48" on conventional roads; 60" × 60" on expressways and freeways |
What This Sign Means
Warns drivers that a detour is ahead and that the normal route will be interrupted, prompting them to prepare to follow an alternate path.
California Temporary Traffic Control Use
Used in advance of a detour in a California TTC zone, ahead of the DETOUR route markers that guide traffic along the approved alternate route.
Common TCP Context
- Advance warning ahead of a full road closure with a signed detour
- Used with M4-8/M4-9 detour markers and directional arrows
- Common on local street closures requiring a marked alternate route
California Size Requirements
Typical minimum: 48" × 48" on conventional roads; 60" × 60" on expressways and freeways.
Sizes are CA MUTCD minimums and vary by roadway classification and speed. Verify against the CA MUTCD 2026 (CA MUTCD Part 6 (Temporary Traffic Control), Chapter 6F; warning-sign design in Part 2C), Caltrans sign specifications, and the reviewing agency.
Common Placement on a TCP
Where it sits: Advance warning area, ahead of the work.
CA MUTCD reference: CA MUTCD Part 6 (Temporary Traffic Control), Chapter 6F; warning-sign design in Part 2C.
Los Angeles Area Usage Notes
In Los Angeles, this sign must conform to CA MUTCD 2026. Work in City of LA right-of-way is reviewed by StreetsLA and the Bureau of Engineering (BOE); state highways in LA County are permitted and reviewed by Caltrans District 7; county roads are permitted by LA County DPW. Sizes, retroreflectivity, and placement must meet CA MUTCD minimums — local agencies may require larger signs based on roadway class, speed, pedestrian volume, and proximity to schools or transit.
Common Plan Review Comments
- Sign not shown at the correct advance distance for the posted speed.
- Advance warning sign missing or out of sequence on the TCP.
- Wrong size specified for the roadway classification (conventional vs. expressway).
- Sign sheeting / retroreflectivity class not noted on the plan.
Plan Review Notes
Verify the detour is fully signed from the advance warning through every decision point and back to the original route. Public Ready checks detour continuity on the TCP.
Signs Commonly Used Together
These signs are typically deployed alongside W20-2 on a California TCP.
Rent or Purchase This Sign
Running a detour on a California project? Public Ready can supply DETOUR AHEAD (W20-2) and the full detour sign package.
Official References
- California MUTCD (Caltrans)
Free official resource — opens official government website
- Federal MUTCD (FHWA)
Free official resource — opens official government website
- Caltrans Sign Charts
Free official resource — opens official government website
- FHWA Standard Highway Signs
Free official resource — opens official government website
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.
Related Signs
Need signs for a California project?
Need to rent, purchase, or include traffic control signs on a California project? Public Ready can help with sign rental, purchase, sign packages, TCP sign legends, and permit coordination.