No, I mean 323s: 3-car high-density units running in pairs would be more suited to the triangle services than the low-density 331s. 323s were the original plan for the Airedale electrification until the funding was cut and 308s came instead. Had the original plan been stuck to, the Hunslet TPL factory in Leeds (not far from where the 333s are being refreshed) would have lasted a little while longer.
However it might well have led to there being only 3 car units instead of four, as the production line would not have lasted long enough to see any fourth carriages being built. So the lines would have ended up with less capacity, which could easily have put the skids under projects like Apperley Bridge & Kirkstall Forge.
According to Wiki 6x331 is 408 seats which is only 48 more that a 4 coach 333 (360 seats), due to the low density of the seating. There are definitely more than 48 standing on some of the rush hour Airedale services. Still can't understand why they've gone with an intercity style layout for a commuter rail service. The lack of anything to hold onto in the massive door areas is also a big own goal
Some of the platforms along the Aire & Wharfe can only just about fit a 333, and don't have an extra 48m to spare. So without SDO, the 323s in multiple are a no go.
Just extend the platforms then. SDO is all well and good at the extremities of the Cornish main line, but on a busy route like Airedale it'll only end up leading to ridiculous dwell-times while everyone in the last two coaches shuffles down. It's not as if 6x23m is that long in the grand scheme of things.
We've been waiting a very long time for this. There are some platforms that will be a challenge to make long enough for 6 car 331s, but sadly neither the will nor the money seems to be forthcoming. It may well be that for the time being that extra peak paths may have to be sought, to at least get a couple more commuter runs up the Aire at least until such time as someone puts 2 & 2 together to make for longer platforms (see what I did there). However the 321/322s need replacing one way or another, they have become increasingly unreliable in the last couple of years, and most of us would rather stand for a little while & get home on time than face cancellations, or worse being stuck on a failed 321/322 for hours.
Edit: Its probably also worth mentioning that the 331s are only replacing the 321/322s, not 333s. So while there is a loss in seats, it's only around 25 (309 for a 321/9 as opposed to 284 for a 331/1) so other than the busiest periods, it won't actually make a huge difference, especially as on many morning services people often ignore the middle seats.
