When is it permissible to pass a signal?

Passing a signal generally requires specific conditions to ensure safety and compliance with operational protocols. The mention of specific signal numbers, such as 279, 101, and 253, indicates that these signals may represent particular instructions or conditions that allow for a signal to be passed under controlled circumstances.

For instance, some signals may indicate a permissive aspect that allows train operators to proceed under certain conditions, such as slow speed or when authorized by a dispatcher. Understanding the context of these signal numbers is crucial for safe train operations, as they provide guidance that is based on established rules and procedures within the rail system.

The other options do not encompass the regulatory framework necessary for passing a signal. Simply having no visible obstructions does not equate to the safe passing of a signal, as signals are in place for a reason beyond visibility. Speed limits alone do not dictate whether a signal can be passed; rather, specific instructions indicated by the signals themselves must be followed. Lastly, daylight conditions do not inherently affect the rules governing signal passage, as operational safety protocols are the priority regardless of the time of day.