Final answer:
In the presence of a railroad crossbuck sign, drivers must treat it as a yield sign, stopping for approaching trains and proceeding with caution only when safe.
Step-by-step explanation:
When a driver encounters a railroad crossbuck sign, they should treat it as a yield sign. This means, if a train is approaching or if there are signals indicating a train is near (such as flashing lights or gates lowering), the driver must stop, giving the right of way to the train.
In the absence of an approaching train, drivers should slow down, look, and listen for any possible trains before proceeding with caution across the tracks. It's important to always expect a train at any time, from either direction, on any track, and to proceed only when it is safe to do so.