Light (Rail) Reading: Why the DLR Timetable is Changing

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In many ways the DLR’s story so far is one of five stages – expansion, stagnation, Olympic revival, further stagnation and consolidation. We are now in the transient stage between the last of those two. With timetable and other changes coming, it seems a good idea to turn our eye to London’s premier piece of light rail once again. In a later piece we will look at expected developments for the future.

Whilst some familiarity with the DLR is presumed, we do not expect that readers will necessarily be familiar with its exact workings. Conveniently for this narrative the imminent changes will have more of an impact on one route in particular, whilst longer term changes will affect other routes. So here we focus on the route between Stratford and Canary Wharf. In part two we will look at the routes via Canning Town, and talk of consolidation and intensification.

The Time of expansion

Single track section by Bow Church

A rare example of a current photo that could have been taken at the time of the DLR opening. Approaching Bow Church station from the north

The expansionist phase of the DLR’s operational life lasted a remarkably long time. From its opening day it seemed as if endless expansion was in the offing, with one extension opening after another. All things, however, must end. In 2011 the extension from Canning Town to Stratford International opened and in the aftermath, for the first time ever in the DLR’s history, no further extension was being actively pursued. This hadn’t originally been the plan – there had been an extension to Dagenham Dock in the works but this had been cancelled by the Mayor in November 2008.

It wasn’t just the length of the network that had expanded. Considerable upgrade works had taken place to allow three-car trains with each of the cars articulated and 28 metres long (excluding coupler). At the time much was made of the fact that a 3-car DLR train was almost as long as a Circle line train, with about the same amount of passenger area. The message seemed to be that the DLR was not a lightweight railway and its potential was just as great as the Underground.

One thing the DLR particularly had going for it in its later expansion phase was a modern reliable signalling system and and advanced form of Automatic Train Operation (ATO). This at a time when the nearest equivalent on the London Underground was on the Victoria line, which then had a very crude form of ATO dating from the 1960s. In other words, unlike the London Underground at the time (and to a large extent now), the expansion of the DLR was not hampered by signalling capability.

Stagnation

The change in approach to the DLR probably happened early on in the financial crisis of 2007-2008 with the Mayor’s cancellation of the proposed extension to Dagenham Dock. The extension relied on a large new housing development, which was clearly not going to happen on the scale (physical or temporal) previously anticipated. The momentum had gone out of that expansion project.

This wasn’t to say that all expansion work ended. The extension to Stratford International, planned long before London was selected to host the Olympic Games, was opened much later than intended but still in plenty of time for the Olympics itself. Other extension plans were much more ambitious though and required capital spending that simply was not going to happen in the newly austere financial climate.

Alongside this a new constraint began to play an increasingly problematic part. Lengthening trains beyond 3-cars was going to be very difficult and very expensive to do. Expansion wasn’t a such a good idea if the existing network would have problems in future just handling the extra traffic that would build up on existing routes. In many ways the DLR was hitting the apparent limit of its scalability.

Olympic Revival

The Olympic Delivery Authority was probably the first in a series of fairy godmothers that turned up to assist the DLR once operational. Of course one could argue that the first fairy godmother was the London Docklands Development Corporation that led to the creation of the DLR in the first place.

With its incredible connections to many of the Olympic sites – most notably Stratford, Excel and Greenwich – the DLR was clearly going to need investment in new trains. It would also be necessary to replace and supplement a lot of equipment to ensure a very high degree of reliability. At a time when new additional rolling stock was badly needed but TfL was already committed to other large expenditure capital projects the intervention of the Olympic Delivery Authority was a very welcome one indeed for the DLR.

Further stagnation

The downside of the Olympic fillip was that once the Olympics were over it was back to business as usual. There was little money available for any expansion and little appetite for it anyway. Even finding money to maintain the existing quality of service seemed to be a low priority compared to other TfL schemes – most notable the development of London Overground. The London Overground, like the Underground, was lengthening its trains. Yet again this helped reinforce a feeling that, as far as development potential goes, the DLR had seen its day.

The only problem was that the one thing that was definitely not stagnating was passenger numbers. In the past year alone passenger journey numbers on the DLR have gone up a staggering 8.5% – compare that with a rise on London Underground of “only” 3.2%. There is no reason to believe that this was freak year and until Crossrail gives a small temporary respite, passenger journey numbers are expected to climb even more.

The need for Short Term Measures

DLR improved service announcement

Recent DLR announcement. Shame about the grammar.

Although a progressive series of measures to improve the DLR had been promised with the awarding of the most recent franchise, it came as a bit of a surprise to discover that that a recent announcement informs us of “Improved frequency and capacity on many DLR services”. Given that there is no more rolling stock, this would appear to be quite difficult to achieve.

A look at the finer details of the new timetable seems to suggest this is the start of a shuffling of services towards a final settled service pattern. Of particular importance in this timetable is the elimination of an operational restriction that has held back the DLR for many years.

A simple, stable but flexible network

The DLR network is very flexible and has some quite complex junctions in order to be able to run a frequent service on many lines without too much conflict between trains. The permutation of services that can be run must be quite considerable but over the years the network has settled down to offer six basic services – although not all of them run all day or every day of the week. During times of disruption or engineering work other routes, such as Woolwich Arsenal to Lewisham, have been run.

In a similar manner to London Underground the service is moving towards a simple peak or off-peak service. However, the morning peak service isn’t quite the same as the evening peak and there is also a revised service when a significant event takes place at Excel.

The City routes

City Routes

DLR routes to the City

To try and make sense of the DLR service structure it is probably easiest to first look at the routes that serve the City. The City is approached from the Canary Wharf/Poplar area by a double track line on an old previously-disused railway viaduct running in approximately an East – West direction. Situated on this viaduct are three stations – Shadwell, Limehouse and Westferry.

The line between Westferry and Shadwell is the most intensively used on the DLR with 30tph – a train every two minutes in peak hours. There are three services that use this section

  • Bank – Lewisham (every 4 minutes)
  • Bank – Woolwich Arsenal (every 8 minutes)
  • Tower Gateway – Beckton (every 8 minutes)

On the diagram above (and in future diagrams) each line represents 7.5tph or a train every eight minutes during the peak period. Because of the way that the DLR now works that line also represents 6tph or a train every ten minutes during the off-peak period. So between Bank and Lewisham there are 15tph in the peaks and 12tph off-peak. Like the Underground, the DLR now tends to run at least 80% of the peak level service in the off-peak period.

It is fairly important that these trains are 3-car trains during the peak rather than 2-car. This is due to heavy passenger demand at Bank. This, of course, does not apply to the Tower Gateway service but as these trains are currently the only ones that serve the Beckton branch in peak hours they really need to be 3-cars long as well. The busiest route, between Bank and Lewisham, has 3-car trains seven days a week whereas currently the other two routes do revert to 2-cars at less busy times.

Shadwell station

Attention tends to focus on the termini in the city but doing so is a mistake. For it is easy to overlook the importance of Shadwell station, not only for origin and destination traffic but also as interchange with the East London Line, and for its position as the final station before the line diverges to serve either Bank or Tower Gateway. Although the island platform is fairly wide it is only really just about adequate to cater for the current level of use. According to the Transport Supporting Paper of the Mayor’s 2050 vision, 25% of the trains go to Tower Gateway but only 10% of the passengers and presumably a lot of people change at Shadwell to minimise the length of time they are in an extremely crowded train. So, as well as the steady trickle of people entering the station, it has to cater for a large number of people alighting at the same time to change trains there.

Both Limehouse and Westferry stations were substantially rebuilt when they were extended as part of the 3-car scheme. Shadwell has been steadily enhanced rather than rebuilt despite being much busier than the other two stations. There was vague talk of rebuilding Shadwell station slightly to the west of its current location. This would make it closer to the other Shadwell (East London Line) station as well as allowing it to be rebuilt to a size and standard more appropriate to current usage.

This currently seems unlikely, however, as Shadwell is not one of the DLR stations proposed to be upgraded in the Mayor’s 2050 Vision Transport Supporting Paper. A large Network Rail 33kV substation has also now been built on the site of the former station building of Shadwell Underground station. More than anything else, this substation has probably killed off any chance of a future combined Shadwell station.

Shadwell New Entrance Street Level

New entrance to Shadwell

With little prospect of a new Shadwell station, the existing one has not been forgotten and has recently had its emergency exit at its eastern end upgraded to a second entrance and exit. This will be more convenient for some locals and should reduce overcrowding at the original entrance. It is also a very pragmatic decision because the former emergency exit did sometimes get used by some people as a short cut to exit the station anyway. Completion of this new entrance means that Shadwell, Limehouse and Westferry stations are all double-ended. This is something one would initially hardly think necessary with the DLR and is something one tends to associate more with Crossrail.

The oddball route: Stratford – Canary Wharf – Lewisham

We now look at the fourth route on the DLR. This is a relatively short but busy one from Stratford (regional) to Canary Wharf. It is the only route that varies between morning and evening peak hours with half the trains extended to Lewisham in the morning peak but none in the evening peak. It is also the only route on the DLR with single track sections which obviously make it more difficult to run a frequent service. The single track sections are between Bow Church and Pudding Mill Lane and between Pudding Mill Lane and Stratford.

Stratford - Lewisham

Stratford – Canary Wharf extended to Lewisham in the morning peak only

The route between Stratford and Canary Wharf is self-contained and does not share track with trains on any other route. In many ways therefore it is a pity that trains are extended to Lewisham in the morning peak as this means it is dependent on what happens elsewhere on the network.

While all of the DLR has seen remarkable growth the Stratford – Canary Wharf route is exceptional, even by DLR standards. It started off as a ten-minute service of single car trains between a single short bay platform at Stratford and the Island Gardens terminus. Originally it was entirely single track between Bow Church and the single platform at Stratford. As traffic grew that single platform at Stratford became quite a problem because of the number of people boarding and alighting.

In the intervening period since opening the narrow single platform terminus at Stratford had been replaced by a wide double sided platform capable of holding three car trains. A short passing loop was also added at Pudding Mill Lane and a fairly cramped station with an island platform was subsequently built at that location.

Whilst the combination of the short passing loop and the two platform terminus allowed a more frequent service it was still very restrictive. A 5 minute interval was the best that could be realistically managed in the most favourable conditions and, for various reasons, a 6 minute interval was considered a more realistic minimum headway. Despite the millions already spent on the DLR east of Bow Church it seemed that yet more money needed to be spent to provide an adequate service.

Pudding Mill Lane station

Whilst Pudding Mill Lane was (and is) generally an exceptionally quiet station, it became clear before the Olympic Games that it would have to be closed during the games as it would be unable to handle the large crowds who would then want to use it. It was also clear that, if the planned sporting legacy use for the Olympic site were to come to fruition and Pudding Mill Lane station was to be a part of that plan, the station would have to be rebuilt to handle large crowds.

Approach to Pudding Mill Lane platforms

Approach to Pudding Mill Lane from the east

The second fairy-godmother to come along and help the DLR was Crossrail. The original site of Pudding Mill Lane was exactly where Crossrail wanted to build a tunnel portal. So Crossrail built a bigger and better Pudding Mill Lane station just to the south of the previous one. This opened in April 2014. The diverted route was required to have double tracking through the station (as before) and provision for double track throughout the diverted route. By paying Crossrail for the additional cost of installing more double track than originally intended on the eastern side, the DLR got not only a new station large enough to handle sports events in the Queen Elizabeth Olympic Park but also a reduction in the length of single track between Pudding Mill Lane and Stratford.

At the time of opening TfL issued a press release promising improvements in the future but offering nothing at the time. In particular the press release stated that:

Completion of the double tracking work at both ends of the site has enabled a capacity of 6,600 passengers per hour in each direction. The current frequency of ten DLR trains per hour delivers a capacity of 5,500 passengers per hour in each direction.

A crucial 4 minute frequency

We have already seen that the busy route to Lewisham has a train every 4 minutes to and from Bank and some morning peak period trains from Stratford are extended from Canary Wharf to Lewisham. It follows that if trains are to run from Stratford to Lewisham then these trains have to be spaced apart by 4 minutes or a multiple of 4 minutes to fit in the gap between the Lewisham – Bank trains. This then also determines the frequency on the Stratford – Canary Wharf section. With a train from Stratford to Lewisham every 12 minutes, as was the case, the maximum realistic frequency between Stratford and Canary Wharf was every 6 minutes with half the trains continuing to Lewisham.

Double track to single track west of Pudding Mill Lane

Double track goes to single track west of Pudding Mill Lane with obvious opportunities for further doubling of the track

The frequency on the the Bank – Lewisham route pretty much determines what frequencies can be run on the Stratford – Canary Wharf route. It would be almost impossible, for example, to have a train from Stratford to Canary Wharf every 5 minutes if some of those trains were to continue to Lewisham. One could do it if only every one train in four went to Lewisham because that would mean a train every 20 minutes and 20 is divisible by 4. However that would mean just three trains an hour. One could of course abandon a fixed interval time timetable between Stratford and Canary Wharf and have an erratic one but this is not just unpopular with the public, it leads to some trains being overcrowded and consequently the timetable being less reliable with knock-on effects elsewhere.

Approach to Pudding Mill Lane and Crossrail Portal

Approaching Pudding Mill Lane and the site of the Crossrail Portal from the east

The big surprise of the new timetable is that instead of running every 6 minutes in the morning peak between Stratford and Canary Wharf and every 12 minutes between Stratford and Lewisham, the trains now run every 4 minutes between Stratford and Canary Wharf and every 8 minutes between Stratford and Lewisham. Given that some trains on this route were previously 3-car it follows that even if every train is now 2-car there will be some capacity increase as well as an obvious frequency improvement. Indeed the trains will all be 2-car but the DLR nevertheless proclaims a 20% improvement in capacity. By an extraordinary coincidence, or possibly not, the press release of around 16 months previous promised an increased capacity from 5,500 to 6,600 persons per hour – an increase of 20%.

Between Lewisham and Canary Wharf there will now be 22.5tph instead of 20tph. The 15tph to Bank remains the same but the Lewisham – Stratford service will now be 7.5tph instead of 5tph. The service will be on an 8 minute cycle with a Bank-Stratford-Bank-(gap) pattern. In principle, if you had the rolling stock, there would appear to be no reason why you couldn’t extend all trains from Stratford to Lewisham to give a 2 minute service (30tph) between Canary Wharf and Lewisham. Fairly obviously, if you had the rolling stock, all trains could be extended to 3-car.

Unlike on the Underground, a 4 minute turnround per platform on the DLR at Lewisham is achievable without the added complexity of “stepping back” drivers and there should be no reason why it cannot be sustained. The DLR has the twin advantages that the trains are relatively short so clear the crossover outside the station quite quickly and, with a train captain opening and closing the doors from any doorway in the train, a train can depart from a terminus within seconds of arrival provided the passengers have all alighted or boarded.

Necessity or desirability?

The timetable improvement of services between Stratford and Canary Wharf has the feeling of an improvement being brought in before the planners really wanted to in order to cater for demand. The line is due to be double-tracked all the way from Pudding Mill Lane to Stratford in 2018-19.

Single track section shortly after leaving Stratford

Single track section shortly after leaving Stratford

In some doubt is just how much will be double-tracked between Pudding Mill Lane and Bow Church. Some TfL sources say that all of this will be done but others suggest that the tight curve just north of Bow Church station (in the very first photograph) will not be doubled. A look at Google Earth suggests double-tracking west of the River Lea (to the west of Pudding Mill Lane station) to Bow Church station may be problematic.

Magnify the map to explore between Bow Church and Pudding Mill Lane stations to appreciate the difficulties of double-tracking between these locations

A further increase in service capacity is promised as a result of completing the double-tracking. Whether this translates to a further increase in frequency as a result of the additional length of double track or whether the capacity increase is achieved solely by replacing the 2-car trains with 3-car trains – or their similar trains of an equivalent length – remains to be seen.

Looking further Ahead

Having finally slain the operational restriction that for many years was holding the DLR back on one of its more overcrowded routes, the way is now clear to develop so that it has a consistent regular frequent service on all branches. To do that more rolling stock will be required. In a future follow-up article we will look at longer term plans, future rolling stock provision and also look at the routes through Canning Town in more detail.

Written by Pedantic of Purley