What must drivers avoid when they see a 'Road Closed Ahead' sign?

When drivers see a 'Road Closed Ahead' sign, they must avoid traveling on the closed roadway because it indicates that the road is not safe for use. This sign informs drivers that there is an obstruction, construction, or other hazardous conditions further along, which may pose risks to their safety. Continuing onto a closed road can lead to dangerous situations, including collisions, becoming stuck, or encountering unexpected obstacles.

While the other options may be actions that drivers might take when encountering this sign—changing lanes may be necessary to avoid a roadblock, slowing down could be prudent for safety, and looking for alternative routes is generally wise—these do not directly address the critical and immediate concern of not entering a closed roadway. Recognizing the instructions given by such signage is essential for maintaining safety on the roads.