W20-4 One Lane Road Ahead
Warns that two-way traffic will be reduced to a single shared lane ahead, where opposing directions must take turns through the work area.
- Sign Name
- One Lane Road Ahead
- MUTCD Code
- W20-4
- Official designation
- One Lane Road (with distance) — FHWA SHS 2024, App. B5-26
- Sign Category
- Warning Signs
Specifications
- Shape
- Diamond
- Color / legend
- Orange background, black legend
Sizes & Dimensions (inches)
These are dimensions shown on the linked layout. Select the required size using the applicable MUTCD and agency requirements; the smallest drawing size is not necessarily the permitted minimum.
Dimensions are side lengths of the diamond, not its corner-to-corner span.
- Layout 130" × 30"
- Layout 236" × 36"
- Layout 348" × 48"
When & Where It's Used
- Alternating one-way traffic control through a work zone
- Paired with W20-7 Flagger and BE PREPARED TO STOP
- Common on rural two-lane roads and bridge or culvert work
Placement Context
- Where it sits
- Advance warning area, ahead of the work.
- CA MUTCD reference
- CA MUTCD 2026 Chapter 6H — TTC Zone Warning Signs
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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. Local jurisdictions may impose additional requirements, and final selection, placement, and dimensions may require engineering judgment or agency approval. Reference editions: California MUTCD 2026 (effective January 18, 2026) and the Federal MUTCD 11th Edition with Revision 1.
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