I posted this somewhat extensive text over on wnxx, admittedly under a different context, but as debate has passed on the future of 153s, it seems somewhat pertinent here. Note the disclaimer that we don't yet have a clear view of what is to happen at Northern, so there be some misinterpretation of the various 'suggestions' as to what will happen there.
We know that the new Northern franchise should be Pacer-free by the end of 2018, if all goes to plan (let's call it 2019 to be safe-ish) with deliveries of new stock, electrification and 15x/170 cascades from elsewhere. GWR should also be free of its small fleet of 8 during 2017, which leaves just the 30 units in Wales.
Comment has been made about the possibility of all the 143s and 144s being made PRM compliant and drifting to Wales eliminate the 142s, which we know can't/won't be made PRM proof, but scant comment has been made about the future of the 153s (and 155s, which are assumed to be staying at Northern). Piecing together what we know or suspect from Northern's possible plans and other confirmed/suspected moves, would the solution of 3-car PRM compliant 153 - 155/3s for the sake of discussion - be a more politically acceptable and more economic solution to removing the last Pacers from traffic? I know there has been serious concerns about the longevity of the 153s and economic sense of PRM-proofing them (principally the super bog), but surely the case for 3-car sets with only 1 super bog must be looked at? With inside cabs and existing toilets to be removed/dismantled/space used for luggage/tip-up seats etc, a 3-car set of around 70m and seating of 210 pax is a pretty much a spot-on replacement for the 62m long pairs of 142/143s on the Valleys, seating around 200? Surely 'selling' the idea of upgraded 155/3s to Welsh users to replace the Pacers as a 'temporary' fix until electrification eventually happens by 2025 (?) will more acceptable than either ePacers or D78s?
Logic goes something along of the the following... Just some thoughts...
Current situation:
Angel AT (30 units) ATW x5, GWR x9, NOR x10, EMT x6
Porterbrook PB (40 units) - ATW x3, GWR x5, NOR x8, EMT x11, AGA x5, LM x8 + NOR 14x 155 vehicles (7 units)
2016: Changes planned (* not known if PB or AT units are involved in these moves yet)
1x PB* unit NOR to EMT (Barton service)
6x AT* units GWR to LM (vice 3x 150/1 to NOR)
giving...
AT ATW x5, GWR x3, NOR x10, EMT x6, LM x6
PB - ATW x3, GWR x5, NOR x7, EMT x12, LM x8, AGA x5
2017/18: Changes Planned/Possible
10x AT units & 7x PB units at NOR displaced by new units/15x cascades, to ATW
3x AT units & 5x PB units at GWR displaced by 15x/16x cascades, to ATW
6x AT units LM displaced by Chase line electrification, to ATW
giving...
AT ATW x24, EMT x6
PB - ATW x15, EMT x12, LM x8, AGA x5
Permits formation of 8x AT 155/3 & 5x PB 155/3 for Wales 13x 155/3 replace 26x 142/143
2018/19: Changes Possible
5x PB units at AGA displaced by 5x 156 ex-ScotRail, to EMT
8x PB units at LM displaced by 8x 172 ex-LOROL/Goblin electrification, to EMT
AT ATW x24, EMT x6
PB - ATW x15, EMT x12, LM x8, AGA x5
Remaining 6x AT units at EMT displaced to Wales, permitting formation of another 2x AT 155/3 to replace remaining 4x 142/143
Leaves 25x 153 at EMT and 14x 155 vehicles (all PB) at Northern to be combined into 13x PB 155/3 for either EMT or NOR, with exchanges of 156s to balance.
Final result:
10x AT 155/3 & 5x PB 155/3 for Wales giving 15x 70m/210 pax units to replace 15x 62m/204 pax 142/143 pairings.
13x PB 155/3 for either EMT or NOR