That's a fair point but even so could they currently meet the levels of demand, route capability & specification, if not then alternatives will be sourced as TfW did. Otherwise you risk ending up with fleet shortages when, say your 175s or 230s insist on setting on fire....
None of the new units have that problem though? I don't see how the problems of the 175s (not exactly new units) are relevant here?
Are you implying that between FLIRTS, 80x, the CAF DEMU and Bimode civities, and whatever other manufacturers could undoubtedly deliver, the varying needs across the UK rail network could not be met? If so, why not? if not, what did you mean?
Personally, I see the FLIRT as the ideal replacement for 150s and a bit further away, the other 15Xs: Bimode, level boarding, great passenger comfort (obviously dependent on how it's specced), good performance, meets sprinter differentials and good route capability
Diesel units are already baked in for the foreseeable future. I know politicians say we are committed to decarbonisation by 2030/40/50/60*, but what politicians say, mean & do are usually three very separate things. Their numbers will diminish as electrification grows and alternative power units become more readily available, but I'd put money on them being around in 2060.
(* select one option depending on which politician you are talking to).
so you're going for the committing to diesel for 40 years option I see.
Still, you must see how the risk of early retirement is greater for units that aren't prepared for conversion or bimode already, depending on decisions taken over the next 20-30 years. Units set up for conversion (and bimodes) are a de-risking strategy.
My point is that there would have been a large number of units falling over. It doesn't matter how much resource you put into maintenance, if the product isn't up to scratch then you've serious problems. Northern would not have been able to cope with the performance of these units as it currently is.
I thought you were referencing the LNWR 230s being withdrawn due to vivarail's insolvency. If not, sorry for misunderstanding.
I am aware that the reliability of the 230s isn't exactly were it should be. I still fail to see how problems with a rather ambitious conversion programme of 30 year old units is relevant to new orders though.