Single-track railway

Single track is significantly cheaper to build and maintain, but has operational and safety disadvantages.

For example, a single-track line that takes 15 minutes to travel through would have capacity for only two trains per hour in each direction safely.

These consist of short stretches of double track, usually long enough to hold one train.

Passing loops may also be used to allow trains heading in the same direction at different speeds to overtake.

On single-track lines with passing loops, measures must be taken to ensure that only one train in one direction can use a stretch of single track at a time, as head-on collisions are a particular risk.

In traditional British practice (and countries using British practice), single-track lines were operated using a token system where the train driver had to be in possession of a token in order to enter a stretch of single track.