W9-3 — Interior Lane Shift Ahead
Sign Specifications
| Code | W9-3 |
|---|---|
| Name | Interior Lane Shift Ahead |
| Category | Warning |
| Shape | Diamond |
| Color | Yellow / black |
| CA status | Recognized in the California MUTCD (2026) |
| MUTCD reference | § 2C.41 (MUTCD 11th Edition) |
| CA MUTCD reference | California MUTCD (2026) |
What This Sign Means
The W9-3 Interior Lane Shift Ahead sign is a yellow diamond with a black symbol or legend. It warns road users of interior lane shift ahead ahead so they can adjust speed and position before reaching the condition.
California Field Use
- Alerts drivers to interior lane shift ahead on California roadways approaching and within a work area.
- Selected and spaced according to approach speed and sight distance.
- Often paired with advisory speed plaques where a reduced speed is appropriate.
Where It Goes on a TCP
Advance-warning area — upstream of the condition so drivers can adjust in time.
MUTCD Requirements
The W9-3 Interior Lane Shift Ahead is addressed under Part 2C (warning signs) of the MUTCD 11th Edition (MUTCD § 2C.41). Read the governing standard, guidance, option, and support text in the official MUTCD before applying it.
California Requirements
California adopts this sign through the California MUTCD, sometimes with state-specific sizing or application notes. A common conventional-road size is 36 x 36 in; larger sizes apply on expressways and freeways. Confirm the size and application for your facility against the current CA MUTCD (2026) and the Caltrans sign specifications and Standard Plans.
| Application | Standard Size |
|---|---|
| Conventional Road | 36 x 36 in |
| Expressway / Freeway | 48 x 48 in |
| Minimum | 30 x 30 in |
Common Plan Review Comments
- Advance-warning distance too short for the posted speed.
- Advisory speed plaque missing where a reduced speed is intended.
- Sign legend or symbol not the current MUTCD 11th Edition version.
- Sight distance to the sign obstructed.
Compliance Notes
- Advance distance matches the approach speed.
- Legend is current and legible.
- Mounting height and offset are correct.
Related Signs
Related Compliance Topics
Learn more in Work Zone Layout.
This is an educational reference only. Always verify sign selection, size, placement, and application against the current CA MUTCD 2026, Caltrans sign specifications, Standard Plans, project documents, and the reviewing agency's requirements.