A specific segment of main line track whose limits are defined by fixed signals or mileposts. Operating rules strictly dictate that only one train can occupy this segment at any given moment to prevent collisions. The length of the section determines the line capacity, with shorter blocks allowing trains to run closer together.
Heard on the job
Dispatcher, we're clear of the block section at milepost 42.
Also heard as
- Block
Related terms
Block system
A method of safely spacing trains by dividing the track into segments and controlling entry to each.
Block signal
A fixed trackside light or semaphore that tells an engineer whether the track segment ahead is clear.
Dark territory
A section of main line track that lacks automated block signals.