Combines the word DETOUR with a directional arrow to point drivers toward the correct turn along the detour route.
MUTCD-style sign reference illustration. Always verify against the official CA MUTCD and Caltrans sign charts.
| Sign code | M4-9 |
|---|---|
| Federal code | M4-9 |
| Name | Detour Arrow |
| Category | Detour Signs |
| Shape | Rectangle (Horizontal) |
| Color | Orange background, black legend and arrow (temporary traffic control use) |
| California status | Used in California per CA MUTCD |
| Typical CA minimum size | 24" × 12" (route marker / plaque) |
Download this sign or open the official MUTCD reference.
Official source: FHWA Standard Highway Signs, 2024 (11th Edition) — Guide signs.
Source: FHWA Standard Highway Signs — Public Domain. California: CA MUTCD 2026 (effective Jan 18, 2026).
Files linked from FHWA are official government publications in the public domain. CA MUTCD and Caltrans links open official government websites. Always verify against the current edition.
Combines the word DETOUR with a directional arrow to point drivers toward the correct turn along the detour route.
Combines the word DETOUR with a directional arrow to point drivers toward the correct turn along the detour route. In the field, M4-9 Detour Arrow is typically positioned at the along the detour route at each decision point. Common deployments include decision points and turns along a detour; used in sequence with M4-8 DETOUR markers; common on local-street detours around closures. Always confirm its size, retroreflective sheeting, spacing, and placement against the CA MUTCD 2026 and the reviewing agency before finalizing the traffic control plan.
Placed at detour decision points in California to direct each turn, keeping detoured traffic on the approved alternate route.
Common field deployments
Agency review note
StreetsLA, LA County DPW, and Caltrans District 7 may require larger sizes or additional devices. Verify with the reviewing agency before finalizing the TCP.
Typical minimum: 24" × 12" (route marker / plaque).
Sizes are CA MUTCD minimums and vary by roadway classification and speed. Verify against the CA MUTCD 2026 (CA MUTCD Part 6, Chapter 6F, and Part 2D (Guide Signs)), Caltrans sign specifications, and the reviewing agency.
Where it sits: Along the detour route at each decision point.
CA MUTCD reference: CA MUTCD Part 6, Chapter 6F, and Part 2D (Guide Signs).
In Los Angeles, this sign must conform to CA MUTCD 2026. Work in City of LA right-of-way is reviewed by StreetsLA and the Bureau of Engineering (BOE); state highways in LA County are permitted and reviewed by Caltrans District 7; county roads are permitted by LA County DPW. Sizes, retroreflectivity, and placement must meet CA MUTCD minimums — local agencies may require larger signs based on roadway class, speed, pedestrian volume, and proximity to schools or transit.
Verify arrow direction at every turn and that no decision point is left unsigned. Public Ready reviews detour turn-by-turn guidance.
These signs are typically deployed alongside M4-9 on a California TCP.
Guiding traffic through a detour? Public Ready can supply DETOUR arrow markers (M4-9) for each turn.
Free official resource — opens official government website
Free official resource — opens official government website
Free official resource — opens official government website
Free official resource — opens official government website
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.
To understand the bigger picture around permits, agency review, lane closures, and pedestrian access for work zones using M4-9 Detour Arrow, visit WorkZoneCompliance.com.
Public Ready can help with M4-9 Detour Arrow — including sign rental or purchase, work-zone signs, TCP sign legends, and permit coordination, and agency-review support for Caltrans District 7, the City of Los Angeles, and LA County.
