A capital pedigree

On December 18 2015, the final S-Stock vehicle from the initial order for 1,395 vehicles rolled off the production line. It was unveiled to the press and invited guests at Derby Litchurch Lane.

It will enter traffic later this year and join the rest of the S-Stock fleet in transforming the travel experience for millions of London commuters each week. When the final train is delivered, Bombardier trains will operate on some 40% of the London Underground sub-surface network, including the Metropolitan, Circle, District and Hammersmith and City lines. Some of the trains replaced by the new fleet dated from 1960 and the difference in both performance and appearance is nothing short of transformational. S-Stock trains are now recording reliability figures above 100,000 kilometres per failure, and as signalling systems and power upgrades are completed, so their performance on the LU network will only continue to improve. 

Speaking about Bombardier’s completion of the train order, Mayor of London Boris Johnson said: “These fantastic, air-conditioned trains are playing a vital role in the on-going modernisation of key London Underground lines. It is no wonder they have proven so popular with passengers as they keep them cooler, offer more space and are far more accessible. Their production at Bombardier in Derby is helping to support crucial jobs in manufacturing and I am looking forward to seeing the final trains roll on to the tracks.”

Nick Brown, London Underground Managing Director, said: “Our new trains were an instant hit with our customers and it is easy to see why. With air-conditioning, more space, improved accessibility and better customer information systems, they are a major part of the vital modernisation of the Circle, District, Hammersmith & City and Metropolitan lines. LU’s successful relationship with Bombardier creates thousands of jobs in the UK and is providing superb new services for our customers.”

Per Allmer, Head of Western Europe, Middle East and Africa region at Bombardier Transportation, said: “With the successful completion of the new SSL fleet, together with our previous build of the new Victoria Line trains, we have now delivered more than 1,700 vehicles to London Underground since 2009 and amassed over two million engineering hours’ experience. 

“As the only supplier currently providing air-conditioned stock on the Tube, we’re keen to capitalise on this experience in the future.”

Passengers love the trains, and their fondness for the design will surely increase as the months and years go by and the performance of the trains improves.

The first S-Stock train was delivered in 2009 for testing, and entered traffic between Wembley and Watford on the Metropolitan Line. London Underground initially placed an order for 191 trains, but in July 2015 that was increased by one extra train that was needed because of the Croxley Link extension.

The additional order is for an eight-car train and one spare vehicle. It will operate on the ‘Met Line’, which was the first LU route to benefit from the introduction of a full S-Stock fleet. The trains replaced stock dating back to 1960-1962. 

Bombardier’s S-Stock has revolutionised the London Underground network thanks to its vastly improved interiors that feature air-conditioning and walkthrough gangways - a massive step-change from the 1960 A-Stock they replaced on the Metropolitan Line and the 1969 C-Stock that they replaced on the Circle and Hammersmith & City lines.

Such is their impact on London that the S-Stock was voted the ninth most popular transport design in London in a survey published at the end of 2015. Sponsored by Exterion Media, the ‘Design Icons’ search is part of the ‘Transported by Design’ programme, an 18-month celebration of events, exhibitions and competitions highlighting the role of good design on the Capital’s network. The fact that S-Stock, at less than five years old, came ninth in a list of 100 designs speaks volumes for the popularity of the trains.

Mike Brown, London’s Transport Commissioner, says: “Through our ‘Design Icons’ search we want to showcase how, from the Tube map to the smallest detail of the new Routemaster bus, S-Stock trains and our multi-billion pound upgrade projects, everything is designed with our customers in mind.”

Transport for London put the first S-Stock into traffic on August 2 2010. On that day, Mayor of London Boris Johnson travelled on the train saying: “There cannot be a better way to criss-cross North West London than in this smooth, state-of-the-art addition to London’s infrastructure. This train is literally the coolest ride in town.” 

Working on the Metropolitan Line, the eight-car train was the first of 191 trains to be delivered. The last trains enter traffic later this year on the District Line. Rollout was completed on the ‘Met Line’ first, with a full fleet of S-Stock trains operating by September 2012, followed by the Circle and Hammersmith & City lines by February 2014. 

Because of infrastructure constraints, such as short platforms on the Hammersmith & City and Circle Line platforms at Baker Street, the S-Stock is fitted with Selective Door Opening (SDO). Other platforms have been lengthened to enable the trains to operate. The decision to replace the Circle Line stock ahead of the District Line was also taken because of the condition of the older trains that they were replacing. D-Stock on the District Line had been refurbished in a programme that lasted from 2005 until 2008, and so had plenty of life left in it.

To accommodate the S-Stock, 224 stabling sidings have been modified, and a new stabling facility has been created at Lillie Bridge. 

The trains travel on the 300km of Sub‑Surface Lines (SSL). The introduction of the seven-car ‘S7s’ on the Circle and Hammersmith & City lines increased capacity there by 65%, while on the District Line it will rise by 24%. The longer ‘S8s’ increased Metropolitan Line capacity by 27%. 

The SSL deal cost £1.5 billion and represents the single biggest rolling stock order in Britain.

The S-Stock design is part of Bombardier’s Movia train family. 

Not only are they capable of carrying more passengers than the trains they replaced, but their performance is considerably better, too. While their maximum speed (62mph) may be lower than the trains they replaced, their acceleration is better (2.9mph per second). Such was the difference that during periods of dual-operation S-Stock performance had to be limited to match that of the older trains because of the capability of the infrastructure. 

Overall there is an increase of capacity on the S-Stock. An ‘S7’ has capacity for 865 passengers while an ‘S8’ has space for 1,003 passengers. The latter has a reduction of 32% in the number of seats, but that is offset by the fact that many journeys are much shorter on these routes, hence more standing room is required.

The headline feature of the S-Stock trains is the air-conditioning. This is the first time it has been fitted to an LU train. It was possible on the SSL routes because the wider tunnels allow hot air to disperse, plus around 66% of the SSL network runs above the surface. (See feature on pages 100-103). Additionally, the ‘S7s’ and ‘S8s’ are fitted with regenerative braking, which can return 20% of energy that would otherwise be lost back into the power network. 

Another method of boosting capacity on the S-Stock trains, is the use of through gangways.

This idea first appeared on TfL’s London Overground Class 378s (also built by Bombardier, in 2009) and is being carried over onto the S-Stock. 

This allows passengers to move easily between carriages, and creates extra room for standing passengers. TfL says that through gangways also make passengers feel more secure, as everyone can see along the entire length of the train. 

Seating arrangements vary, depending on the train. ‘S7s’ have longitudinal seating only, which reflects the nature of the routes that they serve. ‘Met Line’ ‘S8s’ feature a mixture of longitudinal and bay seating and dedicated wheelchair spaces. 

Speaking on December 18 2015, Peter Doolin, Bombardier Transportation’s Vice President Projects, Crossrail & London Underground, said of the S-Stock contract: “It has been an absolute pleasure. We have turned the trains out faultlessly.” He praised the team at Old Dalby, where every train has undergone testing before beginning its LU career, and he highlighted the trains’ reliability statistics, stating: “They are now operating 110,000km between service failures.” This has risen from an average of 75,000km per failure, towards the end of 2014.

Also speaking on the same day, at an event held in Derby, was London Underground Managing Director Nick Brown. He said: “It is a great privilege to be here. My first visit (to Derby) was to look at High Speed Train refurbishments, in 1995.

“The most important people are the passengers, and we know that they enjoy travelling on these trains. The craftsmanship and reliability is so good.”

He says the trains are so reliable that he no longer feels the need to attend performance meetings. “I have stopped going because I know they are performing well.”

He also spoke about how the trains’ air-conditioning was improving travel for people during the summer heat and humidity: “People used them just to cool down.”

He explains: “The last train is due to be delivered towards the end of next year. The D-Stock will then be a thing of the past.”

The S-Stock is the perfect tool for Bombardier to demonstrate its expertise to LU. With 1,700 vehicles introduced onto the Tube since 2009, Bombardier
can boast a considerable pedigree in
the Capital.

• This feature was published in RAIL 793 on February 3 2016