Block Signals Block Signals Automatic Block Signals used at the IRM Automatic Block Signals are fixed signals, automatically controlled, at the entrance to a block governing trains entering and using that block.
Signals display aspects which imply a meaning or indication to the crews.
The table following indicates the basic aspects for a single signal head and their meaning. Train may operate at maximum speed otherwise permitted. Train must not exceed 30 mph or the maximum speed otherwise permitted and be prepared to stop at the next ABS signal. Train may operate at maximum speed otherwise permitted. Train will continue on same route at first switch beyond signal.