8 replies to this topic

[Matthew (Admin/MPJ)]

From londonreconnections

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Sub-surface Signalling

This has been rescoped and the contract retendered. This will not take place until the end of this year or early next year, and thus it is unlikely to be completed before 2018.

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I think what this means is that some of the benefits of the new trains won't be as great as the current singal system can't cope with more trains, which I believe were promised to balance the fwer seats on the news trains.

[friday]

I'm not sure if Mike Brown (Managing Director, London Underground) has been misquoted on the London Reconnections blog, but all the information that I have is that TfL are hoping to let the signalling conctract by the end of this year. And the original contract date of getting all the signalling done on all the subsurface lines by 2018 is, as far as I know, in the tender.

In fact I have on my desk a letter written by Mike Brown to my MP, dated 8th June 2010, that states (direct quote) "we are still aiming to have the new signalling operational on the Metropolitan Line by 2016 and across all of the sub-surface lines by 2018". This mirrors all the other information I have from other sources within TfL.

A group of us have been keeping the political pressure up on TfL and the new government to ensure that the funding for the Met Line resignalling is not curtailed or delayed in any way, to ensure that the period between when the new trains arrive and the delay before the new signals arrive is minimised as far as possible. Most of the Met Line MPs are envolved.

Hope this is of some use.

[Matthew (MPJ/Admin)]

I think what this shows is the mess they have got into.

"Nice" new trains, but fewer seats and a number of years before more trains can be run to make up for the fewer seats, even if it all goes ahead as now planned.

[friday]

I think what this shows is the mess they have got into.

"Nice" new trains, but fewer seats and a number of years before more trains can be run to make up for the fewer seats, even if it all goes ahead as now planned.

Oh, I agree its a mess, but utilimately TfL are doing the best with what they have got, and what their lords and masters have given them.
Ultimately what we all need to hope now is that

1. The money for the resignalling is protected
2. They get on with the job as quickly as possible
3. They minimise the impact of the reduction in seats in the transition period.

(If any of you Amersham people also want to write to Cheryl Gillan, please feel free!)

It would appear, through informal comments, that a couple of the major criterias for the resignalling contract are that
a. the system proposed is not in any way bespoke, uses industry standard components, and can be seen working in a few locations elsewhere
b. can be installed with the minimum of disruption and line closures but as quickly and safely as possible

At least with point b. it would seem that TfL are listening to the fact that passengers are fed up not having trains at the weekends. Although I can't imagine we're not going to have *any* closures, I somehow suspect it will be considerably less than say the Jubilee line upgrade.

[Metman]

This is the problem with the new trains. Unless the new ATO signalling is working, I think the S stock is a waste of time. The lack of seats can only be balanced by better frequency. I my eyes, the addition of aircon is hardly a substitute for good trains that could continue to serve the Met, (especially Amersham) well.

[PeterC]

[They minimise the impact of the reduction in seats in the transition period.]
Typical journey last week had empty seats and people struggling to get through the doors. The public have voted with their bums, they don't want 2+3 seating however nice that might be for us in zones 8 and 9 who get to spread out with two people to a 3 seat bench.

[echinosum]

The ultimate constraint on the capacity of the Met line is the track layout, not the signalling system. Whilst there are benefits that can be obtained by improving the signalling, I do not think that it would be wise to attempt substantially to increase the frequency of trains, without attempting to relieve the capacity constraints arising from:

> the number of terminal platforms at the London end, which are just four, being two at Baker St and two at Aldgate
> conflicting and slow movements through the Baker St throat, from pl 2/3 to/from the circle line, and at Aldgate.

A key factor here is that trains do need time to rest at terminal stations to recover to timetable. Currently the two terminal platforms at Baker St are used to run 6 Watford trains per hour and 4 Amersham trains per hour. The Amersham trains run in alternating 10, 20 min intervals, because the Chiltern trains run in the 20 min intervals. So essentially (off peak - when it seems a reliable timetable can usually be run) there are 6 x 10 min slots per hour on each of the two terminal platforms at Baker St, two per hour unused, in the off-peak timetable. 10 min slots, and a minimum turnaround of about 5 mins, gives very little for recovery. The main recovery has to be done at the other end.

Can they really squeeze material extra capacity out of this, given these constraints? Surely it would be wiser to use the benefits of the signalling system to try and run the present timetable reliably.

[Metman]

I don't think it is the off peak timetable that is the problem. Many trains are rather quiet in the slack hours. It is the peak period where there is a problem- especially on the Watford branch.

[echinosum]

I don't think it is the off peak timetable that is the problem. Many trains are rather quiet in the slack hours. It is the peak period where there is a problem- especially on the Watford branch.

Indeed. The point I am making is that it appears that they can run reasonably reliably to timetable in the off-peak, with 10-min slots for turnaround at terminal platforms. I would suggest that is about the limit of the system to run a reasonably reliable timetable, even with improved signalling. They currently squeeze more in during the peak, and as a consequence do not currently run reasonably reliably to timetable in the peak - they obtain nowhere near the relibility levels of mainline railway companies. I notice that in a recent timetable change, I suspect aimed at improving the reliability of the peak, trains on the Amersham branch run at precisely 16 minute intervals, which is 6.25% less than 4 trains per hour. This is surely in recognition of the importance of having enough terminal slot time at the London end. I suspect this involves precisely 8 minute terminal slots at the London end. Can they really run reliably at just 8 min turnaround slots, even with improved signalling? Can they reduce this 8 minutes without chaos? I doubt it.

The first thing they should do, once they have improved the signalling system, is discover whether it gives them sufficient additional capacity to run the current peak timetable reasonably reliably at 8 minute turnarounds. But I suspect that the reason for unreliability at 8 min turnarounds is because it is too short adequately to absorb the knocks resulting from all the capacity constraints elsewhere, even with improved signalling.