Warns that the shoulder is closed ahead and is not available for stopping, disabled vehicles, or travel through the work area.
MUTCD-style sign reference illustration. Always verify against the official CA MUTCD and Caltrans sign charts.
| 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 |
Download this sign or open the official MUTCD reference.
Official source: FHWA Standard Highway Signs, 2024 (11th Edition) — Warning & Temporary Traffic Control signs.
Source: FHWA Standard Highway Signs — Public Domain. California: CA MUTCD 2026 (effective Jan 18, 2026).
Files linked from FHWA are official government publications in the public domain. CA MUTCD and Caltrans links open official government websites. Always verify against the current edition.
Warns that the shoulder is closed ahead and is not available for stopping, disabled vehicles, or travel through the work area.
Warns that the shoulder is closed ahead and is not available for stopping, disabled vehicles, or travel through the work area. In the field, W21-5a Shoulder Closed is typically positioned at the approach to the activity area. Common deployments include shoulder closures for staging, storage, or work space; used with channelizing devices closing the shoulder; common on freeway and expressway shoulder operations. 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 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 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: Approach to the activity area.
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.
Verify the shoulder closure is clearly delineated and that emergency stopping needs are considered. Public Ready reviews shoulder-closure signing.
These signs are typically deployed alongside W21-5a on a California TCP.
Closing a shoulder? Public Ready can supply SHOULDER CLOSED (W21-5a) and channelizing devices.
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.
To understand the bigger picture around permits, agency review, lane closures, and pedestrian access for work zones using W21-5a Shoulder Closed, visit WorkZoneCompliance.com.
Public Ready can help with W21-5a Shoulder Closed — 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.
