W21-5a Shoulder Closed Sign
Warns that the shoulder is closed ahead and is not available for stopping, disabled vehicles, or travel through the work area.
| Sign code | W21-5a |
|---|---|
| Federal code | W21-5a |
| Name | Shoulder Closed |
| 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 that the shoulder is closed ahead and is not available for stopping, disabled vehicles, or travel through the work area.
California Temporary Traffic Control Use
Used in California TTC zones where the shoulder is occupied by work or devices and must be taken out of service for the length of the operation.
Common TCP Context
- Shoulder closures for staging, storage, or work space
- Used with channelizing devices closing the shoulder
- Common on freeway and expressway shoulder operations
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: Approach to the activity area.
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 shoulder closure is clearly delineated and that emergency stopping needs are considered. Public Ready reviews shoulder-closure signing.
Signs Commonly Used Together
These signs are typically deployed alongside W21-5a on a California TCP.
Rent or Purchase This Sign
Closing a shoulder? Public Ready can supply SHOULDER CLOSED (W21-5a) and channelizing devices.
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.