STAY IN LANE Sign Requirements
This guide summarizes the MUTCD requirements and practical application guidance for the R4-9 STAY IN LANE sign. Use this resource to understand when it is required, how to place it correctly, and how to maintain clear visibility for safe operations.
When It Is Used
Used where stay in lane conditions apply on a California project
Where It Applies
At the point where the regulation applies, per CA MUTCD Part 2B.
Placement Basics
Mount at the standard height and setback for the roadway with clear sight lines.
Visibility / Reflectivity
High reflectivity and clear sight lines are essential day and night.
1. When a STAY IN LANE Sign Is Used
The R4-9 Stay in Lane sign is a California MUTCD regulatory sign. It is shown here as an educational reference with the official FHWA Standard Highway Signs layout and California sizing guidance.
- Used where stay in lane conditions apply on a California project
- Selected and sized per the CA MUTCD and the roadway type
- Coordinated with the overall traffic control plan and permit
2. How and Where It Applies
In the field, R4-9 Stay in Lane is typically positioned at the advance warning area, ahead of the work. Common deployments include used where stay in lane conditions apply on a California project; selected and sized per the CA MUTCD and the roadway type; coordinated with the overall traffic control plan and permit. Always confirm its size, retroreflective sheeting, spacing, and placement against the CA MUTCD 2026 and the reviewing agency before finalizing the traffic control plan.
3. Placement and Application Notes
Position R4-9 at the point where the regulation applies, per CA MUTCD Part 2B.
- Place the sign where drivers have a clear, unobstructed view on approach.
- Mount at the standard height and setback from the edge of the traveled way.
- Do not mount with other signs on the same post unless space constraints require it.
4. Standard Sizes and Visibility Considerations
Typical minimum: Per CA MUTCD minimum for the roadway type.
- Choose size based on roadway speed, sight distance, and mounting location.
- Maintain high retroreflectivity for maximum night and adverse-weather visibility.
5. California Notes
R4-9 Stay in Lane is used in California per the CA MUTCD. Confirm its size, retroreflective sheeting, placement, and spacing against the CA MUTCD 2026 and the reviewing agency before finalizing the traffic control plan.
Go to California Notes6. Common Field or Planning Mistakes
- 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.
Related Resources
View All R-Series 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. 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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