Final answer:
Vehicles must stop within 15 to 50 feet of the nearest rail at a railroad crossing when a train is approaching. Safe crossing on foot requires assessing the car's distance and speed, ensuring there is enough time to cross the road safely before the car reaches the crossing point.
Step-by-step explanation:
The requirement for all vehicles to stop at a railroad crossing when a train is approaching is typically between 15 and 50 feet of the nearest rail. This is to ensure that if a train were to approach the crossing, vehicles have sufficient distance to stop safely and avoid any collisions. This distance allows for both the reaction time of the driver and the physical stopping distance of the vehicle under normal road conditions.
When assessing whether it is safe to cross a road on foot with a car approaching, a key factor is the speed of the car and your ability to cross safely before it reaches you. For instance, if a car is traveling at 60 km/hr and you need to walk 4 meters to cross—the width of the car plus an additional safety margin—it is crucial to calculate whether you have enough time to do so. If there is a car approaching at this speed and it is 28 meters away, it might be unsafe to cross, as cars typically cover this distance quickly.