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
- General Meaning
- 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.
- MUTCD Code
- R3-18
- Official designation
- Combination U-Turn & Left Turn Prohibition (R3-18) — FHWA Standard Highway Signs, Regulatory sheet 1-60
- Typical Use
- At the point where the regulation applies, per CA MUTCD Part 2B.
- Sign Category
- Regulatory Signs
Specifications
- Standard Shape
- Square
- Background Color
- White
- Legend / Symbol
- Black legend
- Border
- Black
- Reflectivity
- High Intensity (for nighttime visibility)
- Compliance
- MUTCD / CA MUTCD
Standard Sizes (inches)
- 24 in Square24" × 24"
- 30 in Square30" × 30"
- 36 in Square36" × 36"
- 48 in Square48" × 48"
Material / Application Notes
Prohibiting left turns and U-turns together at closed median openings. Confirm placement and supplemental plaques against the applicable CA MUTCD standard.
View this sign on the Federal MUTCD (FHWA)California Notes
California-specific application notes and adoptions may differ. Review California requirements where applicable.
What It Means / When This Sign Is Used
In the field, R3-18 No Left or U Turn is typically positioned at the advance warning area, ahead of the work. Common deployments include 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. Always confirm its size, retroreflective sheeting, spacing, and placement against the CA MUTCD 2026 and the reviewing agency before finalizing the traffic control plan.
Learn more about No Left or U Turn sign requirementsWhen & 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 on a Traffic Control Plan
- Where it sits
- At the point where the regulation applies, per CA MUTCD Part 2B.
- CA MUTCD reference
- CA MUTCD Part 2B (Regulatory Signs)
- Typical minimum size
- Per CA MUTCD minimum for the roadway type
California / Field Use Notes
Used in California work zones where both movements must be banned at the same approach — for example at a closed median opening carrying opposing traffic, a temporary two-way operation, or a shifted intersection where either a left turn or a U-turn would conflict with construction activity.
In Los Angeles, temporary regulatory changes (speed, one-way, turn or entry restrictions) generally involve LADOT review, and on state highways Caltrans District 7. Regulatory authority cannot be created by signing alone — confirm the change is authorized by the agency with jurisdiction over the roadway.
Common Plan Review Comments
- Temporary regulatory control not warranted or conflicts with existing control.
- Reduced speed limit posted without proper speed-setting authorization.
- Wrong-way protection (DO NOT ENTER / WRONG WAY) missing at closed approaches.
- Sign size not appropriate for the facility.
Confirm the combined left-turn/U-turn restriction is warranted by the temporary geometry and authorized by the appropriate agency. Public Ready reviews temporary turn restriction signing.
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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. Written against California MUTCD 2026 (effective January 18, 2026) and the Federal MUTCD 11th Edition. Official sources last verified June 2026.
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