4D (train)

A tender for the design and construction of 19 double-deck trains was opened on 24 November 1989. The number of carriages to be built was at the discretion of the builder, however it had to comply with capacity and length requirements. After being bogie exchanged, it was transferred to Jolimont Workshops on 18 December of the same year, for an inspection and final fit out. The train's design was based on the Tangara train being built by A Goninan & Co for CityRail 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 the Comeng sets. 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. In addition, the individual carriages were narrower and shorter in both length and width against their predecessors, to fit the Melbourne loading gauge. Altogether, it was 78 metres long; same length as a four-car Harris set, but seven metres shorter that a three-car Hitachi set. ==Service==

The unit broke from Melbourne tradition by being configured as Driving Trailer-Motor-Motor-Driving Trailer (D-TM-TM-D); all other sets in service at the time were configured as Driving Motor-Trailer-Driving Motor (M-T-M). In a further break from tradition, the 4D did not use the 'D' code for a driving trailer, instead it was coded simply as T-M-M-T. The car numbers were also placed far outside the usual range; the 4D was numbered as 6000T-5000M-5002M-6002T. Most of the time the 4D was on the rails, it was parked in the stabling facilities at Bayswater, on the Belgrave line. It first ran under its own power on 27 December 1991, when it conducted a test run to Lilydale and back. By January 1992, it was running tests coupled with a Comeng set, testing for performance, clearances and its effect on signalling. By 28 January of the same year, it was conducting tests between Bunyip and Longwarry, on the Gippsland line. Testing continued through February 1992. ==Disposal==

Ownership of the 4D was transferred back to the Victorian Government's Department of Infrastructure, and the set was moved under its own power to Newport Workshops in December 2002, for long-term storage. By 2004, the set, which was once stored near the Australian Railway Historical Society's railway museum, was transferred to the western side of the workshops, for a potential return to revenue service. However, this did not eventuate, and the 4D remained in storage. ==References==