This guide summarizes the MUTCD requirements and practical application guidance for the R3-7L LEFT LANE MUST TURN LEFT sign. Use this resource to understand when it is required, how to place it correctly, and how to maintain clear visibility for safe operations.
Assigning a mandatory left turn to the left lane at an approach
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 all traffic in the left lane to turn left at the intersection. It is a word-message lane-use control sign that removes any doubt about the mandatory movement for that lane.
Requires all traffic in the left lane to turn left at the intersection. It is a word-message lane-use control sign that removes any doubt about the mandatory movement for that lane. In the field, R3-7L Left Lane Must Turn Left is typically positioned at the advance warning area, ahead of the work. Common deployments include assigning a mandatory left turn to the left lane at an approach; reinforcing lane-use control where lane assignments change in a work zone; paired with pavement lane-use arrow markings. 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: 30" × 30"; 36" × 36" on multilane or higher-speed roadways.
Used in California per the CA MUTCD to require a left turn from the left lane at an intersection or work-zone approach. 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 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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