The New Sub-Surface Timetable: As Good As It Gets?


December, amongst many other things, is a time for timetables. This tends not to get much publicity, particularly for the Underground, as normally there is nothing interesting to report. Superficially little has changed, but beneath the surface there are small but significant changes to the Sub-Surface Railway and some quite significant changes to the Northern Line. Here we take a look at the changes to the Subsurface Railway. We will look at the Northern Line in the near future.

Ringing the changes

As regular readers will know, the Sub-Surface Railway (SSR) consists of the Circle, District, Hammersmith & City and Metropolitan Lines. As these share tracks these are all highly interdependent, so a change in one may well cause a change to all lines. This is what appears to have happened in December 2014 with the most significant changes being on the Metropolitan Line and relatively minor adjustments to the Circle and Hammersmith & City Lines. The District Line is not running any more trains through the centre but is extending some existing services so that they terminate further out.

Things were complicated because the Metropolitan Line operates a leaf fall timetable. In common with many UK railways, this period has been getting later and later in the year and now, rather awkwardly, often spans the annual Network Rail December timetable change. This was the case for the Metropolitan Line and the leaf fall timetable has operated until 27th December. Engineering work on District and Circle Lines for the following three days means that Wednesday 31st December 2014 is supposed to be the first full day of the new timetable on all four Sub-Surface lines.

Cannon Street

Look. No dagger!

Cannon Street tube station open on Sunday

It was inevitable that there would be a new timetable for the SSR. From December 14, Cannon Street tube station has opened on Sundays. On its own, eliminating the anomaly of it being the only tube station that didn’t open on Sunday would be enough to make a new Sunday timetable necessary for all four lines – even though it only directly affects two of them. There was probably no way an additional station call at Cannon Street could have been absorbed into the existing workings. The timetables are so tightly dependent on each other that once one has to be altered it is almost inevitable that all four have to be changed. In fact, the timetablers are probably doing well if they can make the changes without forcing a minor rewrite of the Piccadilly Line timetable as well.

Regular readers will be aware that from early January SouthEastern trains to and from Charing Cross will not be calling at London Bridge for around 20 months. Less well publicised is the fact that Charing Cross and Waterloo East stations appear to have no national rail trains on Sundays during this period either, with all trains terminating at Cannon Street. This means that Cannon Street tube station is likely to be busy on Sundays in future and a realistic dwell time really does need to be factored into a new timetable.

4 trains per hour (tph) extra off-peak from Baker Street to Aldgate

SSR current off-peak

Diagram showing current off-peak frequencies on the subsurface railway

The big change on the SSR is that off-peak there are an extra four trains per hour on the Metropolitan Line from Baker Street to Aldgate. That might not sound like a big change. Indeed it never received a mention in the latest Commisioner’s Report. The significance of it is though that it brings the frequency of through off-peak Metropolitan services from Baker Street to 12. This, combined with the 12tph on the Circle and Hammersmith & City Lines means that most of the northern part of the circle has 24tph – the same as the frequency on the southern part.

It seems that the additional off-peak trains extended to Aldgate are Uxbridge ones that formerly terminated at Baker Street. This change has the additional benefit of having the entire 8tph off-peak Uxbridge service going to Aldgate as well as the Amersham (2tph) and Chesham (2tph). In fact the only off-peak trains that now terminate at Baker Street are the 4tph from Watford. This is quite a change given that 25 years ago all off-peak Metropolitan Line trains terminated at Baker Street.

One slight problem with the 8tph Uxbridge trains arrangements is that they have to fit into a 12tph pattern. Consequently, although trains leave Uxbridge at regular 7½ minute intervals, journey time from Uxbridge to Aldgate alternates between 56 and 59 minutes.

There is a similar problem with interval spacing with the Amersham and Chesham trains which also go all the way to Aldgate. These are further complicated by the need to segregate these from the Watford trains which share the same tracks to Baker Street. There are additional fast tracks but all LU trains call at all stations in the off-peak so the fast lines are unused by off-peak Metropolitan Line trains.

Watford trains terminate at Baker Street so do not have to be delayed to fit into an interval pattern further down the line. Nevertheless other complications lead to slightly lopsided intervals of off-peak trains departing from Moor Park to Baker Street in an alternating pattern 6 and 9 minute intervals with journey times alternating between 33 and 35 minutes.

The off-peak pattern for the Metropolitan Line as described is already believed to be remarkably close to what is intended in 2018 after resignalling. One obvious difference is the proposed 6tph to Watford Junction instead of 4tph to Watford (Met). This could probably be accommodated without too much difficultly once this link opens (now planned for 2018) and too much of a timetable change. Alternatively this could create an opportunity to recast the off-peak timetable if there were notable benefits in doing so.

District Line changes

Looking at the District Line changes in the working timetable we can also see a similar clear intention to move towards the proposed “final” SSR upgrade off-peak timetable. As mentioned at the start, the effect is to extend some existing services to terminate further out.

To quote from the Working Timetable the changes this time include:

During the Mondays to Fridays midday off-peak period and on Saturdays between 07.30 and 20.00, three additional trains will operate with half of the Tower Hill reversing trains (3 trains per hour) extended to operate to/from Barking.

and on Sundays

Six additional trains will operate between 11.00 and 19.00. In this period, trains previously booked to reverse at Barking have been extended to operate to/from Upminster providing a 5-minute interval service. In addition, half of the Tower Hill reversing trains (3 trains per hour) have been extended to operate to/from Barking.

This strongly suggests that here too the intention on the SSR is not to wait for the new signalling (or even replacing the old D stock District Line trains) before implementing the new off-peak SSR timetable previously proposed for 2018. It also goes to show how, more and more, the only real difference between the Saturday and Sunday timetables on many lines is the fact that trains start later on Sundays, take a little longer to reach their regular interval pattern and finish running earlier.

The District Line change highlights how interconnected the subsurface lines are. Because the District now has trains terminating off-peak at Barking bay platform, the Hammersmith & City trains now continue to the sidings to layover before coming back into service.

Why retain some off-peak Tower Hill reversers?

One can ask the question, why bother to extend only half the Tower Hill reversers to Barking? Why not extend all of them? One can think of answers such as a need to provide time for District Line drivers to undergo a conversion course to ‘S’ stock or even a shortage of trains. The off-peak timetable requires 64 trains which is not much fewer than the evening peak (76 trains). Putting it another way, the mileage run on Saturday, without a peak, is already 94% of the mileage run on Mon-Fri. This does not give a lot of opportunity for train maintenance.

In fact, the most likely reason for only extending half the Tower Hill reversers to Barking is to avoid doing anything too dramatic in one go. In other words, try extending half the service and make sure that runs smoothly before going the whole hog. This incremental approach is a frequently observed London Underground way of working. One only has to look at how they are increasing capacity on the Victoria Line by small stages – or alternatively look at the Northern Line (as we shall do in the near future).

What is a bit of a surprise about the off-peak Tower Hill reversers being extended to Barking is that the original board document (admittedly now almost five years old) made no mention of this and rather suggested that they would continue to terminate at Tower Hill. Like other changes there was no hint (e.g. reference in board or Rail & Underground Panel meeting documents) that these were likely to happen in the near future.

All change (of plan)

We last covered the deals of proposed SSR frequency only last year but it seems the plan has already changed since then. Or, to look at it from a different perspective, certain aspects of the new plan are clearly not now dependent on the new signalling and will be introduced by the end of 2014.

Much of last year’s article focused on how the SSR was going to have a very rhythmic timetable with evenly spaced interval between trains. It was basically close to a perfect timetable that had both a frequent and regular service despite the incredible complexity. By introducing an additional 4tph between Baker St and Aldgate in the off-peak 7 days a week, the latest timetable has effectively completed provision of the service around the circle that we were not expecting until 2018. It also makes it possbile for a regular pattern of trains to be run. Eastbound would have the repeating sequence: Aldgate, Circle Line, Aldgate, H&C to Barking. Westbound would be even simpler with trains alternating between Harrow-On-The-Hill (and beyond) and Hammersmith. Almost certainly this is the most regular timetable ever produced for this section of railway in its 150 year history. The introduction of this intensive off-peak service would suggest that the new signalling was not actually a critical factor but having a common rolling stock with identical, improved performance was.

The main SSR circle (the former Circle Line until a couple of years ago) now has 24tph off-peak between Baker St and Aldgate. Between Tower Hill and Gloucester Road it already had this frequency – in fact marginally more at a rather inconvenient 25.5tph until recently. The loss of 1.5tph (a reduction in Circle Line frequency) is arguably more than compensated for by a regularity of service.

It is worth noting that the High St Kensington – Edgware Road portion of the SSR still has a relatively poor off-peak service of 12tph – both peak and off-peak. This is served by the Circle and District Edgware Road – Wimbledon services. What frequency can be run here is effectively determined by how many trains you can get through Praed St junction and onwards to Edgware Road station. The frequency of the Hammersmith & City Line is a factor in this. In reality the Circle and Hammersmith & City need to operate the same frequency and it is also highly desirable that Wimbledon – Edgware Road is also run at the same. Effectively therefore the frequency of High St Kensington – Edgware Road (12tph) is going to be half the frequency of Praed St Junction (24tph) which with current ancient signalling is probably approaching absolute capacity. It will be interesting to see if this junction is resignalled early on in the SSR resignalling scheme and whether advantage will be taken of this at an early stage to improve the frequency of the lines that run through it.

The off-peak that is slightly less than the peak

A theme that occurs in many our reports of services on the Underground is just how close the off-peak service increasingly is to the peak. This is is the case for much of the SSR. Indeed over some sections it is identical. For Baker Street – Liverpool St there are now 27tph in the peak hour (6 H&C, 6 Circle and 15 Metropolitan). This means that the off-peak the service is now almost 89% of the peak service. For the Metropolitan Line as a whole the mileage on Saturdays is around 87.5% that on Mondays to Fridays which, considering that the mileage clocked up by the peak-only Amersham and Chesham fast trains to London is considerable, is surprisingly high.

Good or bad thing?

The intriguing question is whether or not this early introduction of the regular interval working on the off-peak Subsurface Railway is a good or bad thing. Certainly for today’s passengers it is a benefit. London Underground will probably be quite keen to point out that they can run the 2018 proposed off-peak service without being dependent on the delayed resignalling contract. That may save them some political embarrassment. On the other hand the fact that the peak-hour service is little better than the off-peak service also highlights the probable desirability for more trains in the peak period. The extra trains in service will be dependent on the new signalling and it now appears that any pretence that this will be fully in place by 2018, as originally intended, has totally disappeared.

The slightly worrying thing about the improved service is that it is probably being introduced now because of an existing need. One hopes that Crossrail will buy a few years respite but, if this level of service is not adequate in future, it will be hard to see how in the early 2020s London Underground will be able to provide an intensive enough sustainable service on the northern part of the circle – and this is before HS2 arrives at Euston.

Other than extending the remaining off-peak trains terminating at Tower Hill to terminate at Barking, it is hard to see how the SSR timetable can improve further until the replacement SSR signalling is introduced. This is not now expected to be commissioned until the beginning of 2017 at the absolute earliest. So the message is, make the most of the new SSR timetable. For the next few years this is likely to be as good as it gets.

Written by Pedantic of Purley