New state-of-the-art maintenance trains that will be used on the London Underground are being tested in Europe ahead of delivery to London later this year.

A new rail milling train and two multi-purpose engineering trains with bespoke machinery attachments will be delivered ahead of the Elizabeth line opening in December.

The 160-foot-long rail milling train is the first of its kind to be used in the UK rail industry. It is able to scan the rails using electromagnetic crack detection, looking for any defects. If it identifies any issues with the track, it can mill the surface of the rail to remove defects and cracks, reducing wear on the new Elizabeth line train wheels and the tracks. Metal chips will be collected in a container on the train and later recycled as high-quality scrap metal.

The milling process eliminates the problems of sparks, fire and dust created by traditional rail grinding trains, leaving a smoother surface that will provide a quieter, more comfortable ride for passengers. Using this state-of-the-art technology will reduce the need for major track maintenance, meaning less disruption for customers. Manufactured by Austrian company Linsinger in Steyrermühl in Austria, it has two drivers' cabs and space for up to four members of staff as well as a welfare facility.

The two multi-purpose engineering trains, supplied by Plasser UK, have been manufactured by ROBEL Bahnbaumaschinen in Freilassing in Germany. They can be configured to be between 130 and 260 feet long, depending on the task, with a number of modular attachments. The trains' unique gantry system, provides the capability to change a five ton, 115-foot switch rail within the short overnight engineering hours. The trains can also be configured for different purposes using cranes, a scissor lift for working on overhead line equipment or cabling, and a water tank and jet for drainage clearance and tunnel cleaning.

These trains will also be the main way to transport new rail, platform screen doors, station transformers and more, through the central section of the Elizabeth line once stations are complete.

All three maintenance trains are fitted with the Elizabeth line's new central section signalling system, enabling them to move around the railway while passenger trains are still running to maximise the time spent working during the night.

The three trains are designed specifically for the Elizabeth line and are gauged to fit inside the new tunnels and on the central section of the route. The operation and maintenance of the trains will be carried out by GB Rail freight Limited (GBRf). TfL has awarded this contract for a period of five years.