We’re sorry to announce …, part 3

(… continued from We’re sorry to announce …, part 2, posted on 25 Jun 2016).

For southbound classic-compatible trains joining the HS2 Phase 1 link at the Handsacre junction the recommendation in the SYSTRA report to the timetable schedulers is to “plan services with 2 minute 30 second headway and allow two 7.5 minutes gaps in the timetable to accommodate late trains from remote branch lines (or three 5 minutes gaps)”. The report admits that any delays “will necessarily be propagated to closely following trains” but postulates that “the timetabled gaps make it possible to swiftly return to normal service” (see footnote 1).

Assuming a symmetrical arrangement, the first configuration would mean that each thirty minutes would comprise a 7.5-minute gap left free followed by nine train paths for scheduled services, with this sequence then repeated in the next thirty-minute period. The second configuration would be a twenty-minute repeat of a 5-minute gap left free followed by six train paths for scheduled services. Please feel free to correct me if I am interpreting this wrongly, but that implies to me that if a late-running southbound train arrives just as a free gap has ended it would take the next train path pre-allocated to a classic-compatible service, and following trains would all be knocked down one path. However, restoration of normal service would only be possible either if there is a free path that can be used in the current batch of nine (or six), or will have to wait 22.5 minutes for the next free gap to start in the first arrangement, or 15 minutes in the second. So I’m not so sure that the SYSTRA report’s claim that the arrangements have the ability to “swiftly return to normal service” is justified in all circumstances.

The need to be flexible with the slotting of southbound trains into the train path arrangement implies that there must be a facility to slow, or even stop, southbound classic-compatible trains until a clear path on the HS2 link becomes available. In the July 2012 article in Rail Magazine that I referred to in part 2, Professor Andrew McNaughton envisages making the necessary timing adjustments to southbound classic-compatible trains on the fly as it were. In the first place, the professor suggests that timetables should have two or three minutes of retardation built in, so that small running delays will not result in late arrival. Trains running on time could always be slowed, or even stopped, to slot into an allocated train path on HS2. Trains running behind the timetable could speed up to catch the allocated train path (see footnote 2). If the delay is too great to be recovered by travelling faster, then the flexible arrangement of train paths proposed in the SYSTRA report will allow a new path to be found for the late-running train. In the Rail Magazine article, Professor McNaughton recalls that similar adjustments had been necessary “in the old days” for trains approaching the Channel Tunnel through Kent:

“If you were on time, you stood around for a couple of minutes; if you were a couple of minutes late then you went straight through the tunnel; and if you were ten minutes late you waited for the next path.”

The professor describes this technique as “pure stacking theory”, an approach that is facilitated by real-time train planning and the use of a radio control system that advises drivers on optimum speed and braking. Whilst this is all very clever, and appears to be practical, it seems to me that making all but the slightest of adjustments in this way carries the risk of having a knock-on effect on closely following trains – something that, as I mention above, the SYSTRA report admits. Certainly the effects of parking a southbound compatible train south of the Handsacre junction for perhaps, in extremis, fifteen or twenty minutes, with following trains queueing behind until they can take their turn as each next available train path comes around, is hardly an appealing one, and seems far removed from the premium service image that we are being sold by HS2’s supporters.

Moving on to a different, but not totally unassociated, topic, Section 7 of the SYSTRA report presents an analysis of the capacity supported by the West Midlands Delta Junction, north of Birmingham Interchange station and develops an alternative to the track layout devised by HS2 Ltd that the report demonstrates would offer better slot utilisation. For some reason, the Government felt it necessary to redact the majority of this section in the version that it has e-published (see footnote 3). I can see no indication in any of the published information that HS2 Ltd has taken on board the track layout design improvements suggested by the SYSTRA report.

Section 9 of the SYSTRA report makes recommendations to improve capacity (in Sub-section 9.2) and suggestions of further work that is needed (in Sub-section 9.3). The latter sub-section recommends that “a thorough assessment of the robustness of service scenarios should be conducted”, which should include the development of detailed timetables and operational simulations to evaluate those timetables. The report describes this work as “absolutely necessary to draw out hidden issues and establish a high speed rail system that is clearly feasible”.

In his second follow-up FOI request made in March this year, John Marriott asked for “the publication of any more recent reports that have been produced that do confirm the specified reliability and frequency requirements can be achieved”. No such reports were identified in the response, which describes such confirmation as “an ongoing process as design of the railway and systems moves towards a greater level of maturity”. I can only hope that HS2 Ltd does see this as a necessary study, although I find it suspicious that nothing has been published since 2011 that would indicate that progress is indeed being made.

Footnotes:

  1. See Sub-section 5.5 of the report Operational Concept Study, Technical Note: HS2 Capacity and Reliability, SYSTRA, October 2011.
  2. I mention in footnote 7 to part 1 that SYSTRA recommends timetabling on the basis of a maximum speed that is less than the achievable maximum “to allow late-running trains to speed up to recover lost time”.
  3. But you are able to read Section 7 in its entirety in the version of the document obtained by FOI request, which is linked to from footnote 1.
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