Final answer:
The first sign a driver typically encounters when approaching a highway-rail intersection is an advance warning sign, which is critical for road safety and reducing accidents.
Step-by-step explanation:
The first sign drivers see when approaching a highway-rail intersection is usually an advance warning sign. This sign is essential for alerting drivers to the upcoming crossing and indicating the need to be prepared to slow down or stop. Road signs play a critical role in maintaining safety by regulating vehicle speed and pedestrian crossing, especially in areas where there is a significant interaction between vehicles, trains, and pedestrians. It is important for drivers to respect these signs, as they help prevent speeding and reduce the risk of accidents, which can tragically lead to loss of life.