What is the difference between single and double slip points?

A single slip point has one moveable rail that can direct a train onto one of two possible tracks. The single movable rail means that the single slip will allow two exits only in one direction. In the other direction, there will only be one possible exit. This means that single slips are often used as a safety feature at certain intersections where their use can ensure trains heading in opposite directions can safely cross each other but will not end up on the same section of track in a head-on situation.

On the other hand, a double slip point has two moveable rails that can direct a train onto one of four possible tracks. It is used in situations where two tracks cross each other at an angle but in contrast to a single-slip it will allow trains to cross from one track to the other, in either direction. This can be especially useful in busy multi-track scenarios such as a marshalling yard or the busy approach to a large station.

Overall, both types of track switches are useful for creating more complex track layouts and allowing trains to run on multiple tracks, but they can be more difficult to install, operate and maintain than simple straight tracks so they tend to be installed only in specific locations where their flexibility is especially useful.