If a railroad grade crossing has no warning devices or only a crossbuck sign, what is the correct action?

When approaching a railroad grade crossing that has no warning devices or is marked only with a crossbuck sign, the safest and most responsible action is to slow down and then proceed with caution. The crossbuck sign indicates that you must yield to any oncoming trains, but without additional warning signals, the area may be less predictable. By slowing down, you allow yourself enough time to look both ways for any trains that may be approaching. This cautious approach gives you the opportunity to react quickly if a train is spotted or if other vehicles are stopping unexpectedly.

This response emphasizes the importance of vigilance at railroad crossings, particularly when warnings are minimal. The other options promote unsafe behaviors, such as speeding up without assessing the situation or following closely behind other vehicles, which could lead to dangerous outcomes. Stopping completely isn't necessary in this case unless you see or hear a train approaching, which makes the cautious approach the most sensible choice.