These were introduced in 1992 on the Lilydale-Belgrave lines only (not on the Alamein or Waverley lines). They were a prototype. Many station platforms had to have the coping reduced or replaced in order to provide clearance. The trial was a failure because, while the carriages carried more passengers, they also took longer to load and unload, negating any benefits from carriage of extra passengers. They were used as off-peak trains only on the Surrey Hills line. The 4D carriages were based on the Tangara carriage being built by A Goninan & Co for CityRail in Sydney, however they were similar only in terms of interior and exterior bodywork. They were manufactured from stainless steel and were fitted with air-conditioning, tinted windows, and inter-car doors, allowing passengers to access all carriages of the train. A coloured photograph of a double decker train - silver in colour with a yellow and green strip across the front of the train.Double Decker train / through Surrey Hillssurrey hills, trains, tangarra carriage, a goninan & co, 4d train, belgrave lilydale lines