all this is standard class
159 3 car 172 seats - 222 5 car 192 seats
159 6 car 334 seats - 222 10 car 384 seats
7 car 222 (as of now, 4 standard and 3 first class) 236 seats
Converting 2 coaches to standard (should be 66 seats each) would bring out 366 seats.
Only the 159 will take advantage over the 222 on seating capacity if it formed of 8/9 car
That's not like for like, it involves reducing first class capacity on the Meridian fleet but not on a like for like basis on the Class 158/159 fleet, that's a bit naughty.
Class 159/1 (3 car) has 164 standard class seats and 18 tip-up seats (the Class 159/0 has one more tip-up seat). 23 first class seats are also provided (24 for Class 159/0).
Class 158 (2 car) in SWT configuration has 110 standard class seats and 11 tip-up seats. 13 first class seats also provided.
That gives a five vehicle formation 274 standard class seats and 29 tip-up seats. It also provides 36 first class seats.
The 5 car Class 222 units at present are 190 standard, 11 tip-up seats and 50 first class seats.
If it's reconfigured, including removal of the buffet but keeping the same number of first class seats (36/37) you can only push standard seating up by another 22 seats (that's based on the composite vehicle losing 14 first to provide 22 standard seats) which takes you to 212 standard seats. No additional tip-up seats can be provided.
5 car formations:
Class 158+Class 159 = 274S + 36/37F + 29/30 tip-up
Class 222 = 212S + 36F + 11 tip-up.
If you repeat the calculations on a 7 car unit, using 2 x Class 158 + 1 x Class 159, and keeping the first class capacity identical, which in this case is 49/50 seats, the most standard seats you can fit into a 7 car formation is around 326, whilst retaining 49/50 first class seats.
7 car formations:
Class 158+Class 158+Class 159 = 385S + 49/50F + 45/46 tip-up
Class 222 = 326S + 49/50F + 18/19 tip-up
And so it goes on. You're especially screwed if you have to do anything with the 4 car Meridians, which are beyond useless when it comes to capacity - even in an all standard configuration, which you would presumably want, you only get 212 seats and 10 tip-up seats.
Which raises the other obvious question - why would you want to run stock with 4 x 750hp engines on an 85mph line when stock fitted with 3 x 450hp engines provides more capacity at vastly reduced operational cost ?
It's not even as if Class 222s to SWT would provide any increased reliability, Salisbury have the Class 158 and Class 159 fleets absolutely sorted and they're the most reliable DMU stock on the network, they thrash many an EMU.
