What is the maximum speed a train must proceed through a temporary speed restriction?

The correct answer emphasizes that the maximum speed a train must proceed through a temporary speed restriction is specified in the track bulletin. This ensures that train operators are following regulations that take into account the specific conditions of the track, such as structural concerns or maintenance activities, which can vary based on the location and circumstances.

By adhering to the speed detailed in the track bulletin, train crews can ensure safety and compliance with operational rules specific to their rail network. This approach allows for flexibility, as the speed limit may differ from one location to another based on the nature of the restriction in place. The focus is always maintained on safety, ensuring that trains do not exceed speeds that could compromise the integrity of the track or the safety of train operations.

In contrast, the other options do not capture this necessity for specific guidance. While 25 MPH and 20 MPH could be commonly recognized speeds, they do not account for the variations that may be outlined in the official documentation that accompany temporary speed restrictions. Allowing the crew to determine speed based on personal judgment could lead to unsafe situations if those judgments do not align with the established safety protocols.