Exterior-wise, I should've mentioned.
Either way, if you take 2 trains of the same length and put 1 with 3 sets of doors per coach and 1 with 2 sets per coach, there will surely be less seats on the train with 3 doors per coach?
bit off topic I know
No don't apologise for being off-topic, it's actually bang-on topic. The thread is titled: '
Double-decker trains could hit Britains railways to ease overcrowding'.
What we're talking about is how to get the maximum number of passengers from A to B on limited infrastructure, i.e. peak-hours traffic.
Some are advocating double deck trains, which bring with them expensive infrastructure investment and deliver reduced interoperability.
Others say that accepting the universality of a loading gauge that limits us to single-deck rolling stock does not reduce the maximum capacity of a high volume service provided certain well-tried steps are taken to address the types of trains and their operation.
Both single and double-deck solutions have limits of capacity that when reached will take infrastructure investment to a much higher level.
So, what we are talking about is commuter provision. Experience both in the UK and overseas, e.g. Hong Kong, Singapore, New York (they are just three abroad that I have personally experienced) have demonstrated very high passenger throughput with short dwells and close-run trains. Comparing this with Paris RER which I have also used, where boarding and alighting is less well organised by the public. For a start, at busy stops where there is a lot of interchange, the limited space by the doors mean that many passengers have to climb or decend steps before they alight, and those boarding can only enter at the speed of the slowest stair-climber.
Back to your point about 'regional railway'. Whichever route we are talking about, whether it is SWML, Crossrail (1,2,3 etc.) or any other high density service, we are talking about a commuter loading with the average journey time being well under an hour, not an all-day traffic with families sitting around tables sampling the delights of the buffet.
The noisiest few commuters may whinge about their 3 minute frequency trains not being as comfortable as a class 444, but they are thankfully ignored. They would be the first to complain when costs shoot up to pay for the trains that spend 20 hours in sidings collecting a suntan and being washed by rain. So for most passengers, peak or otherwise, the ability to travel reliably with enough space to stand if it is fully loaded and enough seats in quieter periods is the best compromise.