R3-18 No Left or U Turn
Prohibits both a left turn and a U-turn at the location where the sign is posted, shown with the combined left-turn and U-turn arrow symbol inside a red prohibition circle and slash.
- Sign Name
- No Left or U Turn
- MUTCD Code
- R3-18
- Official designation
- Combination U-Turn & Left Turn Prohibition (R3-18) — FHWA Standard Highway Signs, Regulatory sheet 1-60
- Sign Category
- Regulatory Signs
Specifications
- Shape
- Square
- Color / legend
- White background, black symbol, red circle and slash
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.
- Layout 124" × 24"
- Layout 230" × 30"
- Layout 336" × 36"
- Layout 448" × 48"
When & Where It's Used
- Prohibiting left turns and U-turns together at closed median openings
- Temporary two-way or crossover operations where opposing traffic conflicts
- Intersections with shifted or realigned lanes near the work area
Placement Context
- Where it sits
- At the point where the regulation applies, per CA MUTCD Part 2B.
- CA MUTCD reference
- CA MUTCD 2026 Chapter 2B — Regulatory Signs, Barricades, and Gates
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Browse Regulatory Signs
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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