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125mph Great Eastern Mainline
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Try this one from 2013 in the first instance
https://www.railforums.co.uk/threads/ic225-for-geml.88110/page-3#post-1534909
General problem is that there is too much traffic for faster speeds.
You might find some of the discussion in this thread useful as well https://www.railforums.co.uk/threads/london-to-norwich-90-min-timings.178937/ and this one https://www.railforums.co.uk/threads/why-is-the-geml-always-closed-on-weekends.195613/
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Class 170101
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AHBs at Kelvedon means its a no no.
hexagon789
Veteran Member
I think it was previously said that there wasn't much point in doing so given the mix of traffic and relatively modest journey time reductions you'd get anyway for the cost.
Thank you. The thread quoted above is from 2013 and a lot has changed since then (I mean, it seems we are now dropping tilting trains from a line (WCML) that, in 2013, had only just finished being upgraded several years back at the tune of many billions (!) to allow tilting trains to run at 125mph. I digress...).
The checklist above does not seem unsurmontable and when you process each individually, could surely be achieved incrementally over, say, a 10 year period so that we can achieve 125mph. That’s a 25% increase in speed. For the new timetable which has the Norwich - London fast, you would get a material improvement, surely.
By the way, I resent the “it’s only a 4 or 8 min saving” argument. Follow that argument, why not go back to 90mph and lose “just” 4 mins to save some dosh. And then why not go back to 80mph...
My point being that progress is often achieved incrementally, and we should aim for improvement, not more of the same.
The checklist above does not seem unsurmontable and when you process each individually, could surely be achieved incrementally over, say, a 10 year period so that we can achieve 125mph. That’s a 25% increase in speed. For the new timetable which has the Norwich - London fast, you would get a material improvement, surely.
By the way, I resent the “it’s only a 4 or 8 min saving” argument. Follow that argument, why not go back to 90mph and lose “just” 4 mins to save some dosh. And then why not go back to 80mph...
My point being that progress is often achieved incrementally, and we should aim for improvement, not more of the same.
The Norwich in 90 is a political vanity project.
It's much more than limited time savings. An increase in speed reduces the headway.
Political vanity - tell that to Norwich - London commuters!
I’m sure headway concerns could be mitigated. They have on the WCML, ECML, MML, GWML etc.
There are 14 sets of AHB's between Ipswich and Norwich, and three sets of CCTV crossings, you then have the Peterboro service, and the hourly Cambridge, plus numerous freight paths Ipswich to Haughley, overall I would think it was be a vast waste of money to make it fit for 125mph, and of course the OHl would need an upgrade and complete resignalling from Ipswich to Norwich.
The only Nin90 service that is well used is / was the 1900 out of London, don't think many, if any commuters used it London bound
GEML is really just a big commuter line, even as far as Norwich, 100 min run time, is fine for most that use it, plus of course stops at Diss, Stow, Ips, Mantree & Colchester devalues 125mph
The only Nin90 service that is well used is / was the 1900 out of London, don't think many, if any commuters used it London bound
GEML is really just a big commuter line, even as far as Norwich, 100 min run time, is fine for most that use it, plus of course stops at Diss, Stow, Ips, Mantree & Colchester devalues 125mph
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306024
Established Member
Design a 140mph Freightliner then it might be worthwhile 
To get the maximum capacity out of the 60 mile 2 track section of the GEML from Shenfield to Haughley Jn requires all trains to go at roughly the same average speed. The line is simply too busy to be able to path significantly faster trains on a regular basis without compromising that capacity.
Although no one could foresee Covid, all N90 has achieved in practice is to damage other parts of the timetable, which now remain despite the N90 trains not running.
ETCS between Liverpool St and Shenfield is worthy of consideration for a start, but for both operational and financial reasons, rather than put in the speculative ideas section the main idea belongs in the total fantasy section.
To get the maximum capacity out of the 60 mile 2 track section of the GEML from Shenfield to Haughley Jn requires all trains to go at roughly the same average speed. The line is simply too busy to be able to path significantly faster trains on a regular basis without compromising that capacity.
Although no one could foresee Covid, all N90 has achieved in practice is to damage other parts of the timetable, which now remain despite the N90 trains not running.
ETCS between Liverpool St and Shenfield is worthy of consideration for a start, but for both operational and financial reasons, rather than put in the speculative ideas section the main idea belongs in the total fantasy section.
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hexagon789
Veteran Member
Simply trying to be realistic.
Thanks for digging that out. My memory not being what it was I would have been in danger of writing it all again.
The thing is, insofar as the GEML is concerned, not a lot has changed, excluding current events. What has changed is that we have new trains. This will give 4 minutes (possibly more) for ‘free’ without spending billions - and it would be billions - on the infrastructure.
The point is that a 25% increase in speed does not equal a 25% reduction in journey time, because of the station stops and crucially other trains in the way.
And why not go back to 90mph or 80mph? Because you wouldn’t save anything.
But they haven’t. The headway on those lines is (roughly) the same as it was in 1966, 1990, 1985, and 1976 respectively. The exception being Reading.
The headway on the GEML is effectively 2-3 minutes south of Colchester, and ETCS won’t give you anything better.
They‘re back in the base plan from December (yay!) as are the other current missing Norwich services. Going to be interesting to see if they all stay in the plan how they’ll cover all the diagrams ,755s cleared to LIV St by December perhaps?
pdeaves
Established Member
Agreed, 25% increase in maximum is not anywhere near 25% increase in average. As well as the points Bald Rick has said, the faster you go, the worse the acceleration is, so the harder it is actually to make use of the increased permissible speed. Before you hit the top speed you probably need to apply the brakes for the next stop.
When realigning curves for a faster speed, it is possible that land take is required to get the alignment right.
Once all the constraints are considered, it's probably easier to build a new route on a nice straight alignment with few intermediate stops and little other traffic in the way.
306024
Established Member
Indeed. HS5, A straight line would see Norwich to Liverpool St with intermediate stations at Bury St Edmunds and Stansted Airport, with an option to add Steeple Bumpstead
Norwich is a fine city, but simply doesn’t generate sufficient revenue to justify any expense. 4 tracking to Colchester would be nice operationally but pigs will fly first.
depends on the rolling stock chosen. The 745 has 4 tractioned bogies, no reason, other than financial, why there couldn't be 6, 8 or even 12, which would allow acceleration to continue to a much higher speeds. But this would come at significant cost, not only in capital terms in the cost of the extra traction equipment, but also in running costs, as more motors means more amps. More feeder stations with higher power capability would be required. All to save a couple of minutes? Not going to happen.
pdeaves
Established Member
Very true, but my statement still holds. More motors and greater energy consumption would make the effect less but it will still be there (resistance increases with square of speed).
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