How should a train crew proceed when an intermediate signal displays no lighted aspect (dark signal)?

When an intermediate signal displays no lighted aspect, this indicates a dark signal, which is generally regarded in most rail operations as the most restrictive indication. In practical terms, this means that train crews should treat the absence of a displayed signal as a caution or stop indication, similar to if it were showing a stop signal. This procedure is in place for safety reasons; it ensures that the train crew takes appropriate action to avoid potential dangers down the track, such as other trains or obstacles.

By adhering to this guideline, the crew is engaging in a conservative and safe approach, which is crucial in maintaining operational safety on railways. It emphasizes the need for caution and to adopt a defensive driving mindset in scenarios where the signaling system may not be functioning correctly.