W4-1 Merge Sign
Uses a symbol to warn that two lanes of traffic are merging into one, alerting drivers in both lanes to yield and merge safely.
MUTCD-style sign reference illustration. Always verify against the official CA MUTCD and Caltrans sign charts.
| Sign code | W4-1 |
|---|---|
| Federal code | W4-1 |
| Name | Merge |
| Category | Warning Signs |
| Shape | Diamond |
| Color | Orange background, black symbol (temporary traffic control use) |
| California status | Used in California per CA MUTCD |
| Typical CA minimum size | 48" × 48" on conventional roads; 60" × 60" on expressways and freeways |
📥 Sign Files & References
Download this sign or open the official MUTCD reference.
Official source: FHWA Standard Highway Signs, 2024 (11th Edition) — Warning & Temporary Traffic Control signs.
📚 Official Source Files
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.
What This Sign Means
Uses a symbol to warn that two lanes of traffic are merging into one, alerting drivers in both lanes to yield and merge safely.
Field Use Notes
Uses a symbol to warn that two lanes of traffic are merging into one, alerting drivers in both lanes to yield and merge safely. In the field, W4-1 Merge is typically positioned at the advance warning area, ahead of the work. Common deployments include contraflow and crossover merge points; two-to-one tapers where both lanes carry traffic; lane drop approaches in active construction. Always confirm its size, retroreflective sheeting, spacing, and placement against the CA MUTCD 2026 and the reviewing agency before finalizing the traffic control plan.
🟠 Public Ready Field Notes
Used in California work zones at points where two moving lanes of traffic converge — such as a contraflow merge point, a temporary crossover merge, or a two-to-one taper where both lanes are live.
Common field deployments
- Lane closure setups
- Shoulder closure advance warning
- Utility work zones
- Public right-of-way work permits
- Multi-phase construction staging
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.
Common TCP Context
- Contraflow and crossover merge points
- Two-to-one tapers where both lanes carry traffic
- Lane drop approaches in active construction
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
Confirm the merge configuration, taper geometry, and that the symbol correctly represents the merge direction. Public Ready reviews merge signing and taper design.
Signs Commonly Used Together
These signs are typically deployed alongside W4-1 on a California TCP.
Rent or Purchase This Sign
Need a MERGE (W4-1) symbol sign? Public Ready can supply it with the full lane-closure or crossover package.
Official References
- California MUTCD (Caltrans)
Free official resource — opens official government website
- Federal MUTCD — 11th Edition (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
Related Compliance Information
To understand the bigger picture around permits, agency review, lane closures, and pedestrian access for work zones using W4-1 Merge, visit WorkZoneCompliance.com.
Need W4-1 Merge for a California project?
Public Ready can help with W4-1 Merge — 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.