Standardising the sub-surface lines

Source: Rail Technology Magazine March/April 2013

David Waboso, capital programmes director at London Underground, talks to RTM about inspiration from abroad on sub-surface signalling, and progress on cooling the Tube.

London Underground (LU) runs one of the world’s most complex metro systems, carrying millions of people every day. A new signalling system, to be installed with Bombardier as part of a contract worth £354m, aims to provide the flexibility to run more trains and increase capacity, signifi cantly boosting LU’s ability to meet rising demand.

Bombardiers’ Cityflo 650 system will be installed on the sub-surface Tube lines – Circle, District, Hammersmith & City and Metropolitan. The system has previously been successfully implemented in Madrid, without line closures.

RTM spoke to LU’s capital programmes director, David Waboso, about the new system, the difficulties of standardisation, and future technology for the Tube.

Avoiding clunky closures

Waboso said this was a vital consideration for LU when deciding on a new system. The earlier Jubilee line upgrade involved disruptive weekend closures as the railway moved back and forth between the old and new systems, requiring huge amounts of time.

He explained: “It had a very clunky approach to testing, so we were looking around for a solution that didn’t involve that. We do a lot of benchmarking with other metros and we saw that Metro Madrid was doing its resignalling without any closures.

“We went to have a look at that and came back knowing how they did it. We then put that approach into our specifi cation for subsurface signalling and the response we got was very good. Bombardier’s was the best – not just around whole-life costs, but minimising closures.”

As well as improving operational effi ciency, the new system will bring several benefits to passengers, notably the ability to run the new S Stock trains more frequently.

The larger and more comfortable S7 and S8 stock, being delivered by Bombardier Transportation at Derby, is replacing the older rolling stock across the sub-surface lines in a rolling programme until 2016.

The Metropolitan line replacement is the most advanced: all its trains are S Stock, air conditioned, with through gangways and lots of other features such as better passenger information.

The new signalling system means passengers feel more benefit from the improved trains, Waboso said: “The biggest benefit is when you can get these trains at much more frequent intervals, faster journey times. You can move Londoners far more quickly and comfortably for work and leisure.”

680 Old Dalby 4

Reducing wholelife costs

Another benefit is the reduced need for trackside cabling, which Waboso described as part of the whole-life cost calculation of the new system.

He said: “When you assess what kind of system you want, you don’t just look at the cost of the contractor to provide the system – you look at what you have to do as a customer.”

There was a cost to providing and maintaining power and cabling, and maintenance costs of new systems over 40 years can be “two or three times what you buy”.

Waboso added: “It’s a very important consideration. We were looking to reduce the amount of equipment installed as far as we can and then you judge both the capital cost and the operational cost of maintaining it – put both together to come up with the whole-life cost.

“We found that this system had reduced trackside equipment; a better whole-life cost. “And if there’s less equipment on the ground, there’s less to go wrong too.”

899 New Image

Towards standardisation

London Underground now has multiple signalling systems, partly a legacy of the old Public Private Partnership (PPP) contract, which “did not result in standardisation of signalling systems” across the network. This means that trains even have to interoperate across different systems in a single route.

Waboso said: “That’s historical but these things stay with you for a very long time.

Now we’ve got much greater control we are looking at how we standardise – if you look at other industries that’s how they get performance up and costs down. We want to be in that position.”

The next generation of deep Tube upgrades would see standardised trains and LU is considering “how we can standardise our signalling systems across different lines so we don’t end up with a huge number of further types”, Waboso explained.

“We’ve got two or three different systems and the question is whether we try to get even more or if we try to harmonise on those two or three – that’s something we’re looking at,” he added.

Cooling off

Other challenges on the Tube include cooling the deep lines, without expending too much energy on air conditioning.

Once used for many years, the deep Underground achieves a duvet-like layer of warmth, soaking up the heat. The end result of the processes involved in air conditioning, which requires lots of power, is to add even more extra heat.

“You’ve got to fi nd another way to get rid of the heat, or of not producing so much energy from the air conditioning systems,” Waboso said.

But work is ongoing with contractors and educational institutions to solve this challenge, and Waboso said LU was “pretty encouraged by the results”.

He continued: “I think we’ve moved from it being practically impossible to now being very possible.

“If I was a betting man I would say the chance of us putting air conditioning on the next generation of deep Tube trains is now very high.

“That’s a combination of good old research and application engineering, a bit of innovation and the fact that technology has moved on. You can produce more output now with less energy.

“The trains we are making for the new deep tube are such that we are reducing the energy profile anyway, that means that it creates a bit of a budget for the air conditioning kits to create a bit of heat.

“It has to generate some energy; it’s just trying to reduce that.”

Sustainability – the Tube’s USP

LU is also working to improve the sustainability of its trains and stations, with pioneering work at Sloane Square station leading the way on energy efficient estate (see RTM June/July 2012).

Waboso said: “We’re very aware of our social responsibilities and we have a target on not just on carbon emissions but overall emissions.

“The Tube starts from a position of being a very efficient, sustainable form of transport, because it is mass transit.

“Each train holds over 1,000 people; that’s a lot of cars taken off the roads and it moves them far more quickly than cars could. You can get from one end of the Jubilee line to the other in an hour. You try driving that – it’s just a no-brainer.”

He described the ability to move lots of people very quickly as the “USP of the Tube”, and dividing the amount of energy needed by the number of people results in a very low perperson carbon cost. Waboso concluded: “That’s why everything we do to further increase capacity on the Tube is a very good thing, not just from a customer benefit point of view, but also from an environmental point of view.”

For more on the new signalling system, see our interview with Bombardier’s Peter Acton.

Cityflo 650

The upgrade will deliver a new signalling system for 310km of track and 113 SSR stations, equipment installation for 191 S Stock trains, 86 Piccadilly line trains, 49 engineering trains and six heritage trains; one integrated service control centre and back-up facility; seven signalling equipment rooms; and 36 major track layout changes.

The work is due to be complete by 2018, with initial testing to be carried out at the Old Dalby track until mid-2013. Formal testing will start with the first S Stock train fitted with automatic train control (ATC). The test track will eventually be reconfigured to replicate the operational environment of London Underground.

(Images copyright TfL)

Tell us what you think – have your say below, or email us directly at [email protected]


David Edmunds   13/05/2013 at 09:06

Perhaps cooling the deep tunnels should be seen as an opportunity to extract usable heat. The resulting energy can be stored underground (aquifers. unused tunnels, caverns) and used to provide winter heating for Londoners or businesses. Quite large investment required there but surely a lot better than just dumping the energy, which we the travellers have paid for? DE

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