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R1-8 Go on Slow — official FHWA layout

GO ON SLOW Sign Requirements

This guide summarizes the MUTCD requirements and practical application guidance for the R1-8 GO ON SLOW 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 go on slow 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 GO ON SLOW Sign Is Used

The R1-8 Go on Slow 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 go on slow 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, R1-8 Go on Slow is typically positioned at the advance warning area, ahead of the work. Common deployments include used where go on slow 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 R1-8 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

R1-8 Go on Slow 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 Notes

6. 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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