Final answer:
The number on a crossbuck sign at a railroad crossing shows the number of train tracks at that location, which is key for drivers' safety to anticipate multiple trains.
Step-by-step explanation:
The number on a crossbuck sign at a railroad crossing indicates the number of train tracks that intersect the road at that crossing. For example, a crossbuck sign with the number 2 would mean there are two sets of tracks that cross the road in that location.
It is important for drivers to be aware of this because it indicates that they should be looking out for more than one train coming from different directions, and there might be a second train coming once the first has passed. It is essential for safety and is part of railroad crossing regulations to prevent accidents.