This guide summarizes the MUTCD requirements and practical application guidance for the W20-5L LEFT LANE CLOSED sign. Use this resource to understand when it is required, how to place it correctly, and how to maintain clear visibility for safe operations.
Left-lane closures on multilane streets and highways
Advance warning area, ahead of the work.
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.
Warns that the left-hand travel lane is closed ahead and that traffic in that lane must merge right before the work area. The distance legend may read AHEAD, a distance in feet, or a distance in miles.
Warns that the left-hand travel lane is closed ahead and that traffic in that lane must merge right before the work area. The distance legend may read AHEAD, a distance in feet, or a distance in miles. In the field, W20-5L Left Lane Closed is typically positioned at the advance warning area, ahead of the work. Common deployments include left-lane closures on multilane streets and highways; placed in the advance warning area ahead of the merging taper; paired with W4-2L and channelizing devices or an arrow board. Always confirm its size, retroreflective sheeting, spacing, and placement against the CA MUTCD 2026 and the reviewing agency before finalizing the traffic control plan.
Advance warning area, ahead of the work.
Typical minimum: 48" × 48" on conventional roads; 60" × 60" on expressways and freeways.
Used on California multilane roadways to warn of a left-lane closure ahead of the merging taper, sequenced with advance warning and channelizing devices. Choose the distance legend (AHEAD / XX FT / XX MILE(S)) to match the 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.
Public Ready supports sign selection, project-ready sign packages, and equipment sourcing through qualified providers — with expert support built for compliance.
