MUTCD M4-9a: Detour Signs and Plaques

The M4-9a sign is covered in Section 6I.02 of the Manual on Uniform Traffic Control Devices, 11th Edition. Below are the provisions from that section that describe when the sign is used and how it is placed.

What it means and when it is used

• Standard · Required (shall)
  Each detour shall be adequately marked with standard temporary route signs and destination signs.
• Option · Permitted (may)
  Detour signs in TTC incident management situations may have a black legend and border on a fluorescent pink background.

Placement and mounting

• Option · Permitted (may)
  The DETOUR (M4-8P) plaque (see Figure 6I-1) may be mounted at the top of a route sign assembly to mark a temporary route that detours from a highway, bypasses a section closed by a TTC zone, and rejoins the highway beyond the TTC zone. Table 6I‑1. Temporary Traffic Control Zone Guide Sign and Plaque Sizes Sign or PlaqueSign DesignationSectionConventional RoadFreeway or ExpresswayMinimum Exit Open E5‑2 6H.12 48 x 36…
• Guidance · Recommended (should)
  The Detour Arrow (M4-10) sign should normally be mounted just below the ROAD CLOSED (R11-2, R11-3a, or R11-4) sign. The Detour Arrow sign should include a horizontal arrow pointed to the right or left as required.
• Guidance · Recommended (should)
  A Street Name sign should be placed above, or the street name should be incorporated into, a DETOUR (M4-9) sign to indicate the name of the street being detoured.

Where to read the rest

• Full text: MUTCD Section 6I.02: Detour Signs and Plaques
• Mounting height, lateral offset and retroreflectivity for any sign: MUTCD sign placement guide

Related signs in Section 6I.02