49 CFR § 236.403
Signals at controlled point
November 18, 2020
Signals at controlled point shall be so interconnected that aspects to proceed cannot be displayed simultaneously for conflicting movements, except that opposing signals may display an aspect indicating “proceed at restricted speed” at the same time on a track used for switching movements only, by one train at a time.
[49 FR 3386, Jan. 26, 1984]