4D (train) - Design

Design

Built by A Goninan & Co. in 1991, the train's design was based on that of the Tangara train used in Sydney. However it was similar only in terms of interior and exterior bodywork; the train's electrical system was much closer to that of a Comeng, and was incompatible with that of the Tangara. The design was further modified for use on Melbourne's broad gauge track, and its control system was designed specifically to allow in-service coupling and operation with Comeng sets.

It was manufactured from stainless steel, fitted with air-conditioning, tinted windows, and inter-car doors allowing passengers to access all carriages of the train. It had a total passenger capacity of 974 passengers: 346 seated and 628 standing.

As part of the trial, the Belgrave and Lilydale lines were selected as main testing grounds for the unit and necessary works were performed to accommodate the train's somewhat unconventional dimensions. Works were slated for other lines in the suburban system, but it is not known whether they were ever carried out; the train's confinement to the Belgrave and Lilydale lines suggests that they were not. It was known that the train was physically too large for the Jolimont tunnel between Jolimont and West Richmond railway stations on the Hurstbridge and South Morang lines. Given that the train was a demonstrator, it was likely that production designs or future infrastructure plans would have dealt with this.