Final answer:
The number beneath the cross on a RR sign indicates the number of train tracks at a railroad crossing, providing critical safety information for drivers and pedestrians.
Step-by-step explanation:
The number below the cross on a RR sign, which stands for railroad crossing, typically indicates the number of train tracks that cross the road at that location. For example, if you see a number 2 below the cross, this tells you that there are two tracks at the crossing. It's essential to be aware of this information for safety reasons, and it assists drivers in knowing what to expect when approaching and crossing train tracks. It's not just an arbitrary number; it's relevant information that can help prevent accidents and ensure that drivers and pedestrians are making informed decisions at these intersections.