Delaware Administrative Code
Title 2 - Transportation
2000 - Department of Transportation
2400 - Division of Transportation Solutions
2402 - Manual on Uniform Traffic Control Devices (MUTCD)
Part 2 - Signs
Chapter 2D - GUIDE SIGNS-CONVENTIONAL ROADS
Section 2D.17 - ALTERNATE Auxiliary Signs (M4-1, M4-1a)

01 The ALTERNATE (M4-1) or the ALT (M4-1a) auxiliary sign (see Figure 2D-4) may be used to indicate an officially designated alternate routing of a numbered route between two points on that route.

Standard:

02 If used, the ALTERNATE or ALT auxiliary sign shall be mounted directly above a route sign.

Guidance:

03 The shorter (time or distance) or better-constructed route should retain the regular route number, and the longer or worse-constructed route should be designated as the alternate route.