Final answer:
Safety measures including signs, barriers, and derail devices or wheel stops must be provided on spur railroad tracks to prevent the uncontrolled movement of rolling stock and to ensure the safety of workers and the public, analogous to historical and modern transportation safety management.
Step-by-step explanation:
On spur railroad tracks, where there is a risk of a rolling cart contacting another car being worked on, entering a building, or a work or traffic area, safety measures must be put in place. These safety measures generally include warning signs, barriers, and often derail devices or wheel stops to prevent the uncontrolled movement of rolling stock. Specifically, these devices are designed to protect against accidental car movement and ensure the safety of workers and the public. The principles behind their necessity relate to how a stationary object, like an improperly secured rolling cart, can become a hazard if it starts to roll due to uneven tracks, gravity, or inadvertent human interference.
For example, during the historical Pullman strike scenario mentioned, there was a major concern with stationary railcars not just due to logistics but also due to safety, as idle railcars could pose risks if they were unintentionally set in motion. This is analogous to the need for safety devices on spur tracks today. Additionally, just as cities such as New York and Boston dealt with transportation challenges and accidents, similar concerns apply to modern rail traffic safety management in terms of preventing accidents and managing the interface between rail operations and public areas.