MUTCD M4-3P: BUSINESS Auxiliary Plaque
The M4-3P sign is covered in Section 2D.19 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)The BUSINESS (M4-3P) auxiliary plaque (see Figure 2D-5 ) may be used to designate an alternate route that branches from a numbered route, passes through the business portion of a city, and rejoins the numbered route beyond that area.
- Standard · Required (shall)If used, the BUSINESS auxiliary plaque shall be mounted directly above a route sign.
Where to read the rest
- Full text: MUTCD Section 2D.19: BUSINESS Auxiliary Plaque
- 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
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.