British Railways First Generation DMUs Second Revised and Expanded EditionBritish Railways First Generation DMUs Second Revised and Expanded Edition 35. 00 First widely introduced from the early 1950s onwards, the diesel multiple unit represented an attempt to produce a vehicle that would replace steam traction on the country's branch lines and secondary routes at a time when the railway industry was in desperate need of a cheaper alternative to steam in order to improve the finances of these increasingly unremunerative