Distant-only signals are signals that provide signal indications for a signal further down the railroad track, distinct from regular or switching home signals. Depending on the number of cleared blocks at the previous home signal, they can be either repeaters or first-time distant-only signals.
While distant-only signals are not displayed on the dispatcher’s desk, they play a crucial role in regulating train behavior on the railroad. Their positioning on the territory impacts how trains accelerate or brake, as explained below:
When a train passes a regular home signal, the indication given to the driver may provide information about the status of the next signal(s) ahead. Alternatively, if no information is available, the driver must assume that the next signal shows a “stop” indication (although the distance to the signal is known). The driver will maintain an appropriate speed based on this assumption until the train is close enough to the next signal to receive an update on the signal status.
If a distant-only signal is present along the route, the driver can receive an update slightly earlier, as if receiving the information from the previous regular signal, but only to the extent that the previous signal could have shown. This also applies when the previous signal did not provide information about the upcoming signal. In such cases, the distant-only signal acts as a “first-timer,” indicating whether the next block is cleared or not and any potential speed restrictions.
Distant-only signals do not increase the number of blocks signaled from the previous home signal. (For reference, 1-block signals are considered as 2-block signals with the second signal indicating “stop.”) Additionally, distant-only signals may be inactive for certain routes if the distance to the next home signal is deemed too large to be necessary.
Distant-only signals can be assigned trigger functions and may also be located at the entrance of a block.