The New Tube for London (NTfL) is a type of London Underground train to be built by Siemens as part of its Inspiro family at Siemens's factories in Goole (East Yorkshire) and Vienna, Austria. An initial batch of 94 nine-car trains has been ordered at a cost of £1.5bn to replace 1973 Stock trains on the Piccadilly line, with options for a total of 250 trains allowing replacement of all existing trains on the deep-level Central, Waterloo & City and Bakerloo lines. Trains will enter service from 2025, firstly on the Piccadilly line. Trains will enter service with a train operator but equipped to allow for driverless operation in the future.