An interesting video from the 1980s that shows planning for the design of the Tangara trains, it shows how long it takes for large number of people to board and disembark from a train, based on different carriage designs.
The first is the traditional silver set carriage, which has bottlenecks that prevent people walking up and down the stairs more than one person at a time. The improved Tangara design has wider stairs, which allows people to go 2 abreast, thus increasing the speed at which they can board and disembark.
This is important for dwell times: how long a train has to spend at each station. The longer this is, the fewer trains you can run per hour (the headways, time between trains, is longer) and the more one train’s delay impacts on the trains behind it.
Almost 20 years on, the Cityrail network is on the cusp of retiring almost all silver sets once the new Waratah fleet comes online. Doing so could allow network wide improvements to speed and reliability due to shortened dwell times.
(This video was produced by Comeng, who produced the silver L/R/S Set trains in Sydney and a number of trams in Melbourne. However, Tangaras would eventually be produced by Goninan, the same company that made the OSCARs. I’m unsure as to the reason why the Tangara project was shifted from Comeng to Goninan. If you know, then feel free to post in the comments section below.)