Ordered by Crossrail in April 2016 in a contract worth £12m, the MG31 is capable of milling up to 20m of rail per minute.

The 48m-long train is powered by a 839kW low-emissions diesel engine and has a maximum speed of 80km/h for operation between worksites.

The MG31 is equipped with CBTC for operation on the core section of the Elizabeth Line between Paddington and Liverpool Street. It also features a suction system to contain milling chips and grinding dust when operating in tunnels.