What I don't quite understand is that the 6 car 331s were going to run on Skipton - Leeds, yet this isn't possible due to the platform length at Leeds currently. Fair enough - but no platform lengthening works are planned on Airedale any more (I asked NR on Twitter) so presumably SDO is the solution. If so, why couldn't they SDO the doors at Leeds too if they're the last trains into a platform? Or is it that they would foul signals, etc.?
SDO was indeed the intended method, which was highly criticised last year:
https://www.railfuture.org.uk/dl1880
(October 2018 edition)
The second paragraph on page 8 says:
"The Aire Valley RUG said that its line has had no significant improvements since 2001, and suffers from overcrowding: the 4-car Class 333 trains with just 360 seats regularly carry 600 passengers, and even the new 6-car trains promised by Northern will have only 410 seats.
Nor is there currently any plan to extend the 4-car platforms. Passengers on full trains will not be able to get to a carriage from which they can alight. The RUG is campaigning to extend all of these platforms, hitting the local media and meeting MPs, resulting in the issue being raised in Parliament."
Here was some of the resulting media attention (which also made local TV news at the time):
https://www.yorkshireeveningpost.co...es-will-be-too-short-for-new-trains-1-9190752
If there is already a unit in a bay platform at Leeds, an additional 6 coaches would potentially foul the track circuits and block adjacent platforms.
Personally I cant see them being able extend platforms 1-5 at either end to accommodate 10 coaches and the only bay able to is the new platform W whenever that is built
The plan for Leeds includes re-alignment the track into these platforms, which would presumably enable platform extensions to take place at the west end.
https://www.networkrail.co.uk/feeds/new-platform-part-of-two-more-key-upgrades-for-leeds-station/
"A new platform – platform zero – will be the crowning glory of a significant £161m investment in the rail infrastructure that will also see
improvements to the track alignment for more efficient journeys into platforms 1-6, as well as a major upgrade to the signalling across the entire station, in a boost to train service reliability.
Platforms 1-6 will also be lengthened to cater for longer trains with more seats."
Interestingly, if the existing trains are (almost) all 4 cars and the new trains are 3 and 4 cars, but only certain trains intended to run with 6 cars in the peak, this suggests a significant number of services that are currently 4 cars will be reduced to 3 cars. Much of the time, this will not matter, but I am sure there are plenty of "shoulder peak" services and other very busy trains that will suffer from such a reduction in capacity.