What does a red-and-white WRONG WAY sign tell a driver?

Correct answer: D – The vehicle is traveling against the permitted direction of traffic
The WRONG WAY sign warns that you are traveling opposite the permitted direction on a one-way roadway or ramp. Maryland commonly uses it beyond a DO NOT ENTER sign where wrong-way entry is possible. It does not indicate that the entire road is closed or merely prohibit a particular turn.
Source: Maryland Manual on Uniform Traffic Control Devices — § 2B.38, “WRONG WAY Sign (R5-1a)”, Maryland Driver’s Manual — § 4.B, “Regulatory Signs”



