Abellio East Midlands Railway

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RE: Abellio East Midlands Railway

(19/05/2020 06:16)SK15 GZG Wrote:  According to Eversholt:

Class 158 maximum acceleration: 0.8ms-2
Class 170 maximum acceleration: 0.5ms-2

So the Class 158s have better acceleration and reach their maximum speed sooner

Not all 158s have the same type of engines - some have 350hp engines, others 400hp. I believe the ex-Wessex Trains ones have the inferior type which was why FGW kept the ex-TPE 158s and returned the ex-Wessex ones.

Based on Eversholt's acceleration graphs there's little difference up to 100km/h (62.5mph), between 100km/h and 125km/h (78mph) the 400hp 158 is noticeably better than the 170 but that isn't the case with the 350hp 158. Over 125km/h the 400hp 158 remains noticeably better than the 170 but at this range the 350hp 158 also outperforms the 170.

So the question is perhaps how much 100mph running is there, how much time can that save and is that more than the extra time spent accelerating above 62.5/78mph?

Also worth remembering the 158s have narrower doors and they are slow to open, compared to newer trains so the introduction of 170s should make it possible to reduce dwell times. It might be that they can do Liverpool Lime Street to Manchester (with calls at South Parkway, Widnes and Warrington) faster than 158s but then lose time on other sections.

As an aside Network Rail's rolling stock strategy looked at whether replacing 142s and 150s with cascaded 170s would have any effect on journey times and their models found journey times could improve on routes where there were frequent stops. Although, Northern have apparently found reliability of 170s on Harrogate stoppers isn't good.