Im of the opinion that Chiltern getting 170s from TPx was the plan all along. Like for like TPx have ended up with more vehicles thanks to the 350s. All part of the bigger scheme when the franchises across the north are merged once again & the fact that chiltern had little chance of ordering new diesel stock.
Glad to see the word 'opinion' in that post. The facts are:
* TPE were due to get 40
additional carriages in CP4 in the form of new DMUs but due to new electrification plans that changed to 40 additional carriages in the form of EMUs. If it was the plan to cascade the 170/3s away then it would have been shown as 22 additional carriages on the HLOS.
* The 185s and 170/3s have never been a large enough fleet to cover the Scottish services, as well as the other TPE services without severe overcrowding.
* As a result of the 350/4s being introduced TPE have proceeded with the plan for 5tph on North TPE as per the Network Rail RUS. The extra services start in a couple of weeks time. Without the 170/3s TPE's new timetable won't work.
* The HLOS for CP5 has 6tph on North TPE starting in December 2016 - the same time as 185s should be freed up from Blackpool services and the Ordsall Chord should open.
* North TPE services should start moving over to electric in December 2018.
The above means TPE should have kept the 170/3s until December 2018. Minister Stephen Hammond has confirmed that TPE will get replacement stock for the 170/3s but hasn't confirmed what.
Chiltern were understood to be looking at using more loco-hauled stock but decided to approach Porterbrook for the 170/3s because it'll be cheaper to lease and operate the 170/3s.
Also Patrick McLoughlin has confirmed that TPE will remain as a separate franchise with the DfT franchise review idea of the routes moving to Northern, EC/XC and EMT not going ahead.
I'm of the opinion had Chiltern not taken the 170/3s then they would have gone to Northern and be supplemented with more 170s (e.g. the LO 172s could go to LM and LM could give up some 2 car 170s.) The reason for this is Network Rail long term rolling stock strategy RUS has identified North West routes that won't be getting electrified as suitable routes to cascade 'type 2' regional DMUs down to, while their proposed platform lengthening plans would allow for 4 car 170s at some stations where only a Northern service operate (156s and 158s have slightly shorter carriages to 170s, 175s and 185s.)
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Problem is the 170s on Anglia are used for over 75mph running and timed as such.
Between Norwich and Cambridge and between Ipswich and Haughley Jn / Norwich.
156s will result a journey time penalty with a mximum speed of 75mph, never mind a lowering in journey quality.
If slower rolling stock may be used then the service needs to be re-timed to make allowances for that. If Northern could manage to timetable a peak time Crewe-Manchester service to be 2 x 142s instead of a 323 despite how busy that section of the WCML is then I'm sure Anglia could manage it, if needed, as well.
A 156 would provide around 30 more seats than a 170, so if it's a busy service would it really be a lowering in journey quality?