THROUGH ONLY Sign Requirements

1. When a THROUGH ONLY Sign Is Used

Requires drivers in this lane or approach to proceed straight through the intersection only, prohibiting turning movements.

• Requiring through movement at work-zone approaches
• Restricting turns during construction lane-use control
• Lane-use control where only straight-through travel is permitted

2. How and Where It Applies

In the field, R3-5a Through Only is typically positioned at the advance warning area, ahead of the work. Common deployments include requiring through movement at work-zone approaches; restricting turns during construction lane-use control; lane-use control where only straight-through travel is permitted. 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 R3-5a 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

Used in California work zones where turning movements must be prohibited from an approach, requiring all traffic in the lane to continue straight through.

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.