Can somebody provide some clue as to why these EMUs are to be so heavy, or verify that the 185 tonne figure for each 3-car unit was just a made-up figure used for an applied example in a year 9 science lesson?
The Siemens Nexas (3 cars) and Alstom X'Trapolis 100 (3 cars) used in Melbourne are only a couple of metres shorter than the A-City, and come in at only 121 tonnes, albeit without the need for an AC transformer which alone cannot account for the 64 tonne difference.
The Bombardier 160/260 EMUs used by QR are also only a couple of metres shorter and also narrower, and they come in at 128 tonnes. As the A-City design is the newest evolution based on the 1980s AdTranz design (i.e. the next evolution after the QR 160/260 and Transperth B-series) this example is most important.
I accept that ours are a different design (or at least a new generation based on the same original design) to the other relatively recent types mentioned above, having slightly larger bodies to take advantage of slightly more generous gauging and various other miscellaneous updates. But a couple of metres should not account for a penalty that is equivalent to adding one and a half cars.
I would be disappointed at what would be a clear failure of the procurement process if we end up with the EMUs being any heavier than 125 tonnes each. The point of using an external electricity supply instead of on-board internal combustion engines is to reduce weight - which has the advantages of increased performance, increased efficiency and (very importantly in Adelaide where track maintenance requires a capital works program) less impact on the track. If the cars end up being 60-65 tonnes each compared to the current 46-48 tonne 3000/3100 cars it will have been a step backwards.