One engine in steam is a fundamental method of safe railway working used on single-track branch lines or isolated spurs. By physically allowing only one locomotive to possess the token or authority for that section, head-on collisions are mechanically and procedurally impossible. It eliminates the need for complex signaling hardware on low-traffic routes.
Heard on the job
We work the quarry branch under one engine in steam, so once we lock the switch behind us, the block is ours all day.
Related terms
Block system
A method of safely spacing trains by dividing the track into segments and controlling entry to each.
Tokenless block
A signaling system for single-track lines that uses electrical interlocking instead of physical tokens.
Dark territory
A section of main line track that lacks automated block signals.