Rail Adhesion Trains (RATs)

A C69/77 stock train converted to be a Rail Adhesion Train (RAT) on the Metropolitan line.

Every now and again I see these Rail Adhesion Trains, usually in the Autumn/Winter months and usually at Watford Metropolitan line station, but I never understood what they did.

Coming back from London, last Sunday evening, a Rail Adhesion Train was in the sidings, so I took a photograph and decided to do so some research to find out what this train actually does.

Brief History

The first RATs were used on the Piccadilly line, in 2017, and were converted 1973 stock trains.

Rail Adhesion Trains (RATs) are integral in keeping London Underground running, especially those lines that are predominantly above the surface: Bakerloo, Central, Metropolitan and Piccadilly.

In the Autumn, when the leaves begin to fall and rain and moisture are more common, the crushed leaves form a mulch that sticks to the rails, making adhesion of the train wheels to the track a problem. This can cause delays as train wheels slip on the track or the train simply cannot collect power from the electrified rails. 

This is when RATs begin to appear on the lines.

A converted A60 Subsurface Stock (RAT) and an S8 stock on the Metropolitan line at Watford.

The converted trains usually have the seating ripped out and engineers load the RAT with buckets of gel which are connected to outlets. These can then be sprayed onto the track to help clear the line ahead and improve adhesion.

Some of the newer trains, like the S8 stock, have sanding and deicing equipment on them, but the RATs are still needed.