W4 Series — Merge and Lane Change Warning Signs
Warning Signs · CA MUTCD Part 6, Chapter 6F
The W4 Series covers warning signs for merging lanes, added lanes, and lane-change conditions. In temporary traffic control, W4-2 (ADDED LANE) is used when a temporary lane is introduced — such as when a shoulder is opened as a travel lane or when a realigned lane configuration adds an approach. These signs help drivers anticipate a change in the number of available lanes before reaching the transition.
California Field Use Notes
W4-2 is commonly used at the upstream end of a temporary lane addition or when a contraflow or cross-over configuration introduces a lane that drivers would not normally expect. Advance placement follows the same distance table as other W-series signs in the advance warning area.
Showing 2 of 2 signs
Uses a symbol to warn that a travel lane is ending and that traffic must merge in the indicated direction where the roadway narrows.
Uses a symbol to warn that two lanes of traffic are merging into one, alerting drivers in both lanes to yield and merge safely.
Educational 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.
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Public Ready can help you source, rent, or purchase W4 Series signs and integrate them into a compliant traffic control plan. For work zone compliance support, visit WorkZoneCompliance.com.