This guide summarizes the MUTCD requirements and practical application guidance for the M4-8P DETOUR sign. Use this resource to understand when it is required, how to place it correctly, and how to maintain clear visibility for safe operations.
Used where detour conditions apply on a California project
Along the detour route at each decision point.
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.
The M4-8P Detour sign is a California MUTCD detour sign. It is shown here as an educational reference with the official FHWA Standard Highway Signs layout and California sizing guidance.
The M4-8P Detour sign is a California MUTCD detour sign. It is shown here as an educational reference with the official FHWA Standard Highway Signs layout and California sizing guidance. In the field, M4-8P Detour is typically positioned at the along the detour route at each decision point. Common deployments include used where detour conditions apply on a California project; selected and sized per the CA MUTCD and the roadway type; coordinated with the overall traffic control plan and permit. Always confirm its size, retroreflective sheeting, spacing, and placement against the CA MUTCD 2026 and the reviewing agency before finalizing the traffic control plan.
Along the detour route at each decision point.
Typical minimum: 24" × 12" (route marker / plaque).
M4-8P Detour is used in California per the CA MUTCD. Confirm its size, retroreflective sheeting, placement, and spacing against the CA MUTCD 2026 and the reviewing agency before finalizing the traffic control 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.
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