MUTCD M4-1P: Alternative Route Auxiliary Plaques
The M4-1P sign is covered in Section 2D.16 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
- Option · Permitted (may)Alternative Route auxiliary plaques (see Figure 2D-5) displaying legends such as ALTERNATE, BY-PASS, BUSINESS, or TRUCK, may be used to indicate an alternate route of the same number between two points on that route.
- Standard · Required (shall)If used, the Alternative Route auxiliary plaques shall be mounted directly above a route sign.
Where to read the rest
- Full text: MUTCD Section 2D.16: Alternative Route Auxiliary Plaques
- Minimum sign sizes by roadway type are in the size section for this chapter: Section 2D.05
- Mounting height, lateral offset and retroreflectivity for any sign: MUTCD sign placement guide
Related signs in Section 2D.16
Source: Manual on Uniform Traffic Control Devices, 11th Edition (Federal Highway Administration, December 2023, public domain). Excerpts are shortened and shown out of context; read the full section before specifying a sign. Your state may still be operating under the 2009 edition or a state supplement. Official manual: mutcd.fhwa.dot.gov.