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.
MUTCD-style sign reference illustration. Always verify against the official CA MUTCD and Caltrans sign charts.
| Sign code | W21-7 |
|---|---|
| Federal code | W21-7 |
| Name | Utility Work 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 |
The official dimensioned layout drawings below show the exact border widths, legend and letter heights, spacing, corner radius, and the standard sizes used to fabricate W21-7. Use them to confirm sign sizing for your road type before finalizing a traffic control plan.
| Application | Size |
|---|---|
| Conventional roads | 48" × 48" |
| Expressways & freeways | 60" × 60" |
Source: CA MUTCD Part 6F (TTC) & Part 2C (warning sign design). Confirm the exact size for your road type and speed against the current CA MUTCD and the official layout drawing.
Layout drawing extracted from the FHWA Standard Highway Signs (public domain). Verify exact dimensions and sizes against the current CA MUTCD, Caltrans sign specifications, and Standard Plans for your application.
Download this sign or open the official MUTCD reference.
Official source: FHWA Standard Highway Signs, 2024 (11th Edition) — Warning & Temporary Traffic Control signs.
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 sourcesWarns 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 that utility work is taking place on or near the roadway ahead, alerting drivers to utility crews, equipment, and possible lane or shoulder impacts. In the field, W21-7 Utility Work Ahead is typically positioned at the advance warning area, ahead of the work. Common deployments include utility maintenance and installation in the right-of-way; short-duration and mobile utility operations; encroachment-permit work for utility agencies. Always confirm its size, retroreflective sheeting, spacing, and placement against the CA MUTCD 2026 and the reviewing agency before finalizing the traffic control plan.
Used by utilities and their contractors in California right-of-way for water, power, gas, and communications work that affects the roadway.
Common field deployments
Agency review note
StreetsLA, LA County DPW, and Caltrans District 7 may require larger sizes or additional devices. Verify with the reviewing agency before finalizing the TCP.
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.
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.
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.
Confirm utility-specific warning is used and that permit conditions are reflected in the TCP. Public Ready supports utility encroachment-permit signing.
These signs are typically deployed alongside W21-7 on a California TCP.
Doing utility work in the right-of-way? Public Ready can supply UTILITY WORK AHEAD (W21-7) and the full sign package.
Free official resource — opens official government website
Free official resource — opens official government website
Free official resource — opens official government website
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.
This sign is commonly used in shoulder and utility work zones. Learn more about work zone layout requirements, setup, and field readiness at WorkZoneCompliance.com.
Learn more at WorkZoneCompliance.comPublic Ready can help with W21-7 Utility Work Ahead — including sign rental or purchase, work-zone signs, TCP sign legends, and permit coordination, and agency-review support for Caltrans District 7, the City of Los Angeles, and LA County.
