Further down the line

I have been prompted to post this blog by comments made on this site about the likelihood that four tracks will be required on the base of the ‘Y’ at some stage in place of the two currently-planned for HS2. This is not a topic that I have researched in any depth and I cannot claim any particular expertise in the design of railway tracks. Consequently, I would ask you to regard this blog as something akin to a “stream of consciousness”, rather than a fully considered piece of work – the latter being the standard to which I normally aspire. No doubt, those of you who are more expert in these matters will put right any errors, or misconceptions, that are evident in this piece.

As I understand it, there are three reasons to prefer four tracks over two: resilience, reliability and capacity.

What I mean by “resilience” is the ability to overcome equipment failure, and particularly a broken down train on the track. On a two-track line such a blockage is problematic; four tracks offer the ability to by-pass such a problem. It appears that HS2 Ltd is alert to this potential shortcoming of a two-track design, and has come up with the solution of inserting short (approximately 2 km) sections of four tracks into the otherwise two-track railway – not something that was in the design that was submitted to public consultation, of course. The candidate locations for these “sidings” were announced to those communities affected during the September round of community forum meetings. The one nearest to me happens to be in the general locality of Priors Hardwick and Wormleighton – an area about which I had expressed deep concern in my blog This blessèd plot (posted 29 Aug 2011). Well done HS2 Ltd! What a great choice!

Of course the term “siding” probably gives the wrong impression. I expect that HS2 Ltd will want to have some means of safely detraining passengers, so maybe some sort of platform is on the cards, and perhaps a temporary shelter (and what about electric power and toilets), and even a road to get buses in to ferry passengers away. But this is just speculation on my part, as HS2 Ltd has not been too forthcoming with the details.

So perhaps HS2 Ltd has a sort of solution, provided that the stricken train can get to (or be towed to) the nearest siding. But, neither the siding solution, nor a four-track configuration come to mention it, offers much resilience against a major incident, such as a derailing. Thoughts of a derailing prompt me to comment that sidings mean points on the through line, and the thought of a trains crashing over points at speeds well in excess of 200 mph is one that I am not totally happy with.

The second of my three reasons is “reliability”. On a two-track railway an otherwise on-time service can be made late by a slower train ahead. With four tracks it is usual to designate one up track and one down track as “fast” and the other two tracks as “slow”. This allows slow and fast services to be segregated.

In my view, the chief threat to reliability on HS2 will be delays resulting from running “classic compatible” HS2 trains on the West Coast Main Line. Once trains are running on the high speed tracks then they should all be able to proceed at the same place, rendering overtaking unnecessary. So I can’t see that having four tracks for HS2 would offer any particular advantages on this score.

My final reason for going to four tracks is capacity. Now I can’t see that the number of seats on offer from a two-track railway will be a problem for many years to come. On the contrary, the problem that HS2 is going to have is filling all those seats, bearing in mind that it will be restricted to passengers between a small number of locations. An illustration of the size of this problem is the assumption in the HS2 business plan that by 2037 24% of passengers will classified as “new trips”, a point which I commented on in my blog It’s nothing short of a miracle (posted 17 Feb 2012). I find it a staggering assumption that almost a quarter of HS2 passengers will be people who wake up one morning in Birmingham, say, and decide, presumably on a whim, that they will travel to London for no other reason than that this will give them the opportunity to use HS2. What rubbish – some people perhaps might do this once, but a quarter of passengers, day after day!

Where HS2 might have a capacity issue is on the number of train paths accommodated. An assumed service specification diagram published by HS2 Ltd as Figure 7 page 67 of the January 2012 document Economic Case for HS2: Updated appraisal of transport user benefits and wider economic benefits requires 17 train paths to be available in each peak hour on the base of the ‘Y’ (from Birmingham Interchange to London) in order to support the basic “day one” ‘Y’ route service.

Now opinions vary on the number of train paths that HS2 will be able to support; the official HS2 Ltd figure is 18 per hour, but some experts feel that even 17 is more than will be possible. There is also the promise that future improvements in technology will allow more trains to run per hour. Professor McNaughton, in one of his more enthusiastic moments, has forecast that 30 will be possible, one day.

It is also difficult to see circumstances in which new train paths might be required. There are so few stations, and all the basic services have been covered by the 17 paths. Where will the need for new train paths come from?

So perhaps, and it really grieves me to say it, HS2 Ltd may be right in designing for two tracks only – as far as we know anyway, although there is always the possibility that an upgrade to four tracks will be the next bombshell that is dropped at the November round of community forums. Designing embankments, cuttings, viaducts and tunnels from the start to be able to accommodate four tracks in future would be a massive additional cost. Retrofitting four tracks to a route only designed for two tracks would be difficult, expensive and potentially very disruptive to services, but would not be impossible.

However, my view is that the current network design, with a shared section of route for the majority of services (i.e. Birmingham Interchange to London), is very vulnerable. If it did prove necessary to increase the capacity into London at some stage in the distant future, it would be far better, I think, to build a totally different additional route into London, turning the ‘Y’ into an ‘H’.

I hate to have to admit it, but this latter point appears to be one on which HS2 Ltd and I agree. A document issued by HS2 Ltd to give answers to questions raised at a technical seminar and given the reference QA77483 comments:

“Our remit from Government required us to assess whether there would be the demand for a 4-track railway corridor. We decided that this was not necessary for the foreseeable future, and also that there would be very significant engineering difficulty in so doing. Therefore we concluded that should there be a case in the long term for a further two tracks between London and the North of England, it would be more practical and beneficial for them to follow a completely different route, serving other cities.”

I am quite happy to benefit from the reduction in environmental impacts that two tracks offer compared with four, safe in the knowledge that, by the time that the restrictions that this brings are problematic, I will be long dead.


4 responses to this post.

  1. Posted by aboodoo on October 10, 2012 at 10:27 am

    I covered this in my submission to the HS2 Consultation. Currently, there are over 20 trains per hour on the WCML, MML and ECML corridors, and the assumption that one High Speed Line north from London can cater to all of that is ridiculous. Perhaps a second may be added at a later date, but more resilience would be gained from it using a different route, rather than the (then) existing HS2 being 4 tracks.

    Worse still, the section from Birmingham Junction to Y junction will have around 24 trains per hour in each direction, but will be designed for 18. Jonathan Tyler has covered this in writing, I’m afraid I haven’t myself since I’m not really much of a writer.

    Both Jonathan and I know about timetabling and railway planning (although he still makes a living out of it, and I moved into other things), and my suspicion is that it’s yet another thing that the HS2 people haven’t thought about – it was designed by consultants and pitched to Government as a finished design, and then tinkered with. I don’t think it has been properly planned and thought through at any stage, from the routing to the network topology to what the real needs of the railway actually are. I say this, not as an embittered NIMBY, but as a professional Transport Planner and Researcher, and that essentially *is* my professional opinion.


    • Thanks Anzir, I must confess that I hadn’t noticed the “wishful thinking” on the section of track just north of the “delta” junction at Water Orton. The service specification in Figure 7 shows 20 train paths using this section, which are:
      London-Liverpool (2 paths), London-Edinburgh/Glasgow (2 paths), London-Manchester (3 paths), Heathrow-Manchester (1 path), London-Leeds (3 paths), London-Newcastle (2 paths), Heathrow-Leeds (1 path), Birmingham-Manchester (2 paths), Birmingham-Glasgow (1 path), Birmingham-Leeds (2 paths), Birmingham-Newcastle (1 path).
      I would appreciate clarification of the other four that you have identified.
      Will this mean that a section of 4-track line is required north of the delta junction?
      I would appreciate a link to Jonathan Tyler’s work please, if you have it.
      As for your comments to the public consultation being ignored, you are of course not the only expert in this position. HS2 Ltd was not short of expert advice from all quarters as a result of the consultation exercise, but the view appears to be that its own consultants know best (even when they obviously don’t).


  2. Posted by chriseaglen on October 12, 2012 at 7:57 pm

    Your first point about resilience does not cover some of the issues such as pantograph dewiring and it also over states derailments. There are other essential services for maintenance work requiring 4 tracks.

    Second point is not correct about overtaking of slow and fast. Running parallel routes at larger distance spacing is necessary for low adhesion conditions> i would not have called this head reliability/unreliability.

    The third requirement is again not about seats being full because the trains can be halved as occurs with off peak units now, but train paths and the Javelin type services connecting to more locations resulting in demand for more train paths. The passenger numbers 1100 for trains each 8 minutes is not realistic on two tracks as any defect cascades 40km section to a standstill and within 40minutes the route is blocked. The M25 had the two stage expensive development programme HS2 will claim. The buffer zone provides the land take test with the 25m width being sufficent for 4 track at lower speed and 60m being quoted for the 4 track sections. The change is probable in the phase 1 post hybrid period with none able to prevent this step change. The 17 to 18 paths is not sufficient for the newly expanded phase 2 intentions for trains from more towns and cities incuding Scotland. It is about paths and not seats. The increasing train paths on one track with the realities of railway operations is not credible.

    30 paths not possible in some weather conditions and in some breakdown states.

    Stations are the next overlay as people what more. As the sidings become full tracks.

    Javelin services have the stations on and off HS1 and this is not allowed for in the articles. Margate, Ramsgate, Folkestone are not on HS1 but each requires a path.

    The planning is for the long term.

    The H v Y being the reason for 2 is not credible. The planning and design is a story based on illogical railway requirements. Such a national scheme has to be designed for the maximum requirement and then staged for need. This has not happened with HS2.

    The requirements are for transport and rail operation not for infrastructure building. The first two determine the need for the third. HS2 has been attempted the opposite way round we can only accept a bcr of x hence no 4 track as costs too high. We are intercity but now realise suburban commuting is the problem. How inconvienient.

    The Y first phase needs 4 tracks to be effective.


    • Thanks Chris for your corrections and additional points. It is clear that you think that, in trying to be fair to HS2 Ltd in my blog, I have ended up being too soft.
      First of all let me say that I agree with most of what you say. A Y design employing two tracks is clearly the least resilient configuration that you can utilise to connect the four cities. It is also clear that four tracks would facilitate more reliable operations and add considerably to the resilience to unplanned events. The short four-track sections that have been added on to the current design will have limited benefit in this respect.
      It is also bizarre, to say the least, that a network that it being promoted as a way to ease congestion on the existing lines has an obvious inherent train path congestion problem that will act as a straightjacket from day one of the Y network opening. Indeed, according to Anzir Boodoo, in his recent comment on this blog, the Y network north of the West Midlands delta will have insufficient train path capacity to meet the day one service specification assumptions. By the way, the comment about Professor McNaughton and 30 paths an hour was not meant to be an endorsement of what he has said, as I meant to indicate by the phrase “in a more enthusiastic moment”.
      You are also right to point out that HS2 appears to be a long-distance railway that has, as its core raison d’être, the aim to reduce overcrowding on commuter lines, and that is also bizarre.
      I also strongly agree with you that HS2 has not been properly planned, either in an overall transport context or to meet envisaged long-term requirements. Despite all of the work that has been done since March 2010, it remains, at its heart, a “fag packet” design.
      I would have thought that these were issues for pros and antis alike and would welcome serious attempts by HS2 supporters to address the apparent shortcomings of the current design. However, those seeing this invitation as an excuse to repeat the same old HS2 propaganda need not apply.
      What is clear is that a change to a four-track design would make a bad environmental situation worse, and I obviously would not welcome that. Where do you stand on this, Chris?
      A four-track design would also cost far more to implement and, as you rightly point out, would blow apart the business case. This, of course, I would welcome, because it should mean that it will never get built in the first place, resulting in no environmental damage from HS2.
      What I do find incredible is that we are able to have such a basic discussion at this stage of the project and that the points that you have raised have not, as far as I can see, been properly addressed by HS2 Ltd.


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