GEML 110\125mph operation?

[lancededcena]

Sorry if this has been asked before!

Compared to other former InterCity mainlines (GWML, ECML, MML, WCML) I always considered the GEML InterCity to be the odd one out of all of those as it runs only 100mph max (I also don't consider Gatwick Express as an InterCity service either!).

The GEML between Norwich and Haughley Junction (just outside Stowmarket) looks like it is perfectly capable of 125mph operation (if not 110mph), I also do think that the section between Boreham (just outside Hatfield Peverel) and Colchester can be upgraded to 110mph, but of course the Stadlers will have to be regeared for 125 operation which wouldn't be so difficult in my opinion as Norway and Sweden already have Stadler FLIRTs that have a max speed of 200km/h.

What are the roadblocks of upgrading the speed of the mainline, how difficult it would be to upgrade or is it even possible to upgrade the mainline?

 

[JonathanH]

It has been asked before. No chance - too many other trains in the way.

Try this one from 2013 in the first instance. Obviously the higher performance trains now exist.
https://www.railforums.co.uk/threads/ic225-for-geml.88110/page-3#post-1534909

If the crossings were sorted, the signalling upgraded, the OLE retensioned, the power supply strengthened, the track maintenance enhanced (considerably), some bridges rebuilt, some embankments strengthened, places of (staff) safety provided for 100mph+ operation, some track renewed to 100mph+ standards, some of the curves realigned, and some junctions removed altogether, then most of the route is fit for 125. Exceptions are through Chelmsford, Colchester, Manningtree and Ipswich station areas but trains would be stopping there.

Assuming 125 where it is currently 100, and a train of Pendolinesque characteristics, the journey time saving London-Norwich is approx 8mins on today's stopping pattern. Roughly half this saving is due to the better acceleration / braking of the train, and half is due to the raised line speeds. This assumes that all the slower trains in front are shifted out of the way, these being the ones that call at wayside halts such as Shenfield, Witham etc.

With new trains it would be an awful lot of money to save 4 mins. Alternatively knock out a stop for free.

General problem is that there is too much traffic for faster speeds and not enough payback from the additional work.

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/ and https://www.railforums.co.uk/threads/125mph-great-eastern-mainline.210353/#post-4826676

It is a two-track railway and has to do many different things. Moreover, Norwich is only 115 miles from London and the end of the line.

 

[CW2]

Your biggest block (pun intended) would be the signalling system. Higher speeds require greater distances between signals, whereas high capacity requires closely spaced signals. On the GE the emphasis has always been on capacity over outright speed.

 

[edwin_m]

Your biggest block (pun intended) would be the signalling system. Higher speeds require greater distances between signals, whereas high capacity requires closely spaced signals. On the GE the emphasis has always been on capacity over outright speed.

ERTMS helps with this particular issue, but not with the matter of having numerous slower trains that get in the way.

 

[JonathanH]

Perhaps the better question is where a dynamic loop could be put in that would allow trains to make better use of the railway. Basic timetabling principles are that a Southend service precedes the Norwich, that the Braintree leaves the mainline ahead of that and stoppers follow the Norwich train. The freight paths broadly keeps pace with stopping trains.

The 1700 to Norwich has three minutes of pathing time between Liverpool Street and Norwich being right up behind a Witham terminator and not far behind a Clacton train at Colchester. There isn't really scope for it to go faster.

 

[MarkyT]

Your biggest block (pun intended) would be the signalling system. Higher speeds require greater distances between signals, whereas high capacity requires closely spaced signals. On the GE the emphasis has always been on capacity over outright speed.

Although the HST and subsequent fast trains were specified to be able to brake from 125mph to a stand in the same distance as older ones could from 100mph. That is how higher speeds were achieved on other mainlines without wholesale resignalling, although sighting, maintenance access arrangements to equipment, etc all need to be considered and that may result in details of the design being modified to suit the new speed.

 

[Bald Rick]

Your biggest block (pun intended) would be the signalling system. Higher speeds require greater distances between signals, whereas high capacity requires closely spaced signals. On the GE the emphasis has always been on capacity over outright speed.

The biggest block is the timetable. All that higher speeds do is enable you to catch up the previous train sooner.
Also, and I will quote a former Track Engineer for East Anglia directly: “I reckon with a lot of money we could get it to 125mph. However we couldn’t keep it there, and we would have speed restrictions on within a month”

The issue being that what is underneath the ballast is either clay soup or fen, and most of the route has the unusual combination on that geology of regular fast trains plus regular heavy fast freight trains.

Perhaps the better question is where a dynamic loop could be put in that would allow trains to make better use of the railway.

Extending Witham loops nor-eastwards was always the preference. To at least Kelvedon, and possibly Marks Tey. Trouble is, it doesn’t actually provide any more capacity (the next constraint isn’t removed and is just as restrictive) ; it just allows the freight liners to overtake the stoppers!