Final answer:
Protective devices like derailers are required on spur railroad tracks where rolling cars could cause harm, to ensure safety around the railroad infrastructure. These measures help prevent accidents by stopping uncontrolled movement of rail cars. It is true that such safety devices must be provided in potentially hazardous areas.
Step-by-step explanation:
The statement is true. Derailers or other similar protective devices must be installed on spur railroad tracks where there is the potential for rolling cars to move onto mainline tracks, collide with other cars, or enter buildings, work areas, or traffic areas. These safety features are essential to prevent accidental release of uncontrolled railroad cars, which could cause significant damage, injuries, or fatalities. Derailers function by causing the wheels of a railcar to lift off the tracks, effectively stopping any unintended movement. They are a critical component in ensuring the safety of workers, pedestrians, and structures around the railroad tracks.
For instance, when talking about atmospheric pressure and trains, it is dangerous to stand close to railroad tracks when a rapidly moving commuter train passes because the train's motion creates a low-pressure area that can draw objects, including people, towards it. This atmospheric pressure differential can be extremely hazardous.
In the context of tollbooth stations, a wire in the pavement is used as a form of traffic calming or detection device to alert or monitor approaching vehicles. This has less direct relevance to railroad safety but pertains to transportation safety and monitoring systems.