This guide summarizes the MUTCD requirements and practical application guidance for the W1-4b REVERSE CURVE (2 LANES) sign. Use this resource to understand when it is required, how to place it correctly, and how to maintain clear visibility for safe operations.
Two-lane lane shifts around work activity
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 of a two-lane reverse-curve alignment ahead — a curve in one direction followed by a curve in the other — such as a lane shift around a work area.
Warns of a two-lane reverse-curve alignment ahead — a curve in one direction followed by a curve in the other — such as a lane shift around a work area. In the field, W1-4b Reverse Curve (2 lanes) is typically positioned at the advance warning area, ahead of the work. Common deployments include two-lane lane shifts around work activity; temporary alignment changes / crossovers; used with channelizing devices through the shift. 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 where a California work zone shifts two lanes of traffic through a reverse (S) alignment, for example around an excavation or a temporary crossover.
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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