This guide summarizes the MUTCD requirements and practical application guidance for the R3-5a THROUGH ONLY sign. Use this resource to understand when it is required, how to place it correctly, and how to maintain clear visibility for safe operations.
Requiring through movement at work-zone approaches
At the point where the regulation applies, per CA MUTCD Part 2B.
Mount at the standard height and setback for the roadway with clear sight lines.
High reflectivity and clear sight lines are essential day and night.
Requires drivers in this lane or approach to proceed straight through the intersection only, prohibiting turning movements.
Requires drivers in this lane or approach to proceed straight through the intersection only, prohibiting turning movements. 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.
At the point where the regulation applies, per CA MUTCD Part 2B.
Typical minimum: Per CA MUTCD minimum for the roadway type.
Used in California work zones where turning movements must be prohibited from an approach, requiring all traffic in the lane to continue straight through.
Go to California NotesEducational 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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