Final answer:
A steady yellow "X" indicates that drivers should prepare to vacate the lane below the signal as it signifies forthcoming traffic changes or lane closures. It is important for managing traffic flow and safety.
Step-by-step explanation:
A steady yellow "X" signal typically indicates that a driver should prepare to vacate the lane that the signal is over because a change is about to occur. Drivers should move out of the lane safely, in anticipation of the lane being used for opposing traffic or potentially closed. Such lane use control lights are often found above reversible lanes and help manage traffic densities and pedestrian safety. In any event, when encountering a steady yellow "X", one should never ignore it; it acts as a warning to be heeded before the light potentially changes to a steady red "X", which would mean the lane is no longer to be used in your direction of travel.
A steady yellow 'X' on a lane use control light means that you should stop moving and become stationary until it passes by. This is similar to a yellow traffic light at an intersection, which signals caution and prepares drivers to stop. In this case, the 'X' is specifically used for lane use control, indicating that the lane is about to be closed or restricted.