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SSS – Sub Surface Signalling

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London Underground is 150 years old this year. The first train on the Metropolitan Railway ran between Paddington and Farringdon on 9 January 1863.

Today, the Metropolitan line is one of the four lines that make up the sub-surface railway (SSR), the others being the Circle, District and Hammersmith & City. Although they have been upgraded during the last 150 years, they are still some of the oldest parts of the Tube’s network.

Not surprisingly, with an ageing system, it is difficult to achieve reliability; yet London Underground has the objective to provide not only increased reliability, but also a significant increase in capacity, faster trains and a better service for its customers. It will do this by introducing new state-of-the art trains and a signalling system that enables more frequent services.

Largest signalling contract

Bombardier Transportation was awarded the contract for SSR automatic train control (ATC) signalling upgrade for London Underground in June 2011. The contract, valued at approximately £354 million, is reportedly the largest metro re-signalling contract ever undertaken in the world.

At the heart of the new system is Bombardier’s proven CITYFLO 650 ATC system which uses communication-based train control (CBTC) technology. It is similar to that running successfully on the Metro de Madrid Lines 1 and 6 in Spain, part of one of the busiest networks in Europe where the customer has already noted a 30% increase in passenger carrying capacity with further improvement expected. The same system is also in operation on Shenzhen Metro Line 3 in China, which was delivered in 22 months.Under Test At Old Dalby Image1 [online]

CITYFLO is a moving block system utilising modern radio-based wide area networks to communicate between the control centre and the train. In addition to enabling the system to be installed without interruption to service and to tight timelines, it can provide interoperability with legacy train control systems and can be adapted to accommodate country requirements.

The full scope of the London Underground contract is for the signalling renewal and provision of an ATC system for the four sub- surface lines which carry 1.3 million passengers a day. Together, the lines comprise 40% of the network and carry 25% of the total ridership.

By 2018, Bombardier will equip the 310 km of track line (40 km in tunnels), 113 stations, 191 trainsets, 49 engineering trains and six heritage trains, followed by a two-year warranty period.

New methods – one team

The sheer scale of this project has required London Underground to adapt its processes and requirements to the solution that Bombardier is providing. Matthew Steele, London Underground’s programme delivery manager, explained: “We’ve recognised that we need to be flexible as a customer to enable our suppliers to give us the solutions we need. This is facilitated by our ‘New Engineering Contracts’ (NEC) – a very different way of working – and one that reciprocally incentivises collaboration with our supplier partners.

“The sub-surface railway represents 40% of London Underground’s network. We also have to deal with the age of the system and the need for reliability, which means that we want to ensure that the impact on our customers is kept to a minimum.”

The project teams from LU and Bombardier are co-located one building. Matthew Steele is convinced that this was the correct move to make. “It ensures a spirit of transparency and openness and it helps to integrate all the functions – from the operations team, who understand how the railway operates, to the testing team and through to the maintenance staff who will look after the system down the line.

“There are a lot of inter- dependent projects that all have an impact on each other. So we can’t look at re-signalling, rolling out new trains, or maintaining them as projects in isolation. We have to do all of these things together and recognise that the smallest change can impact upon the other initiatives. We can only deliver if we are monitoring all our interfaces and working collaboratively.”CITYFLO antenna [online]

Minimising risk

“Knowing that London Underground is probably the most complex metro in the world, we ran a comprehensive 18-month selection process before embarking on this project. Bombardier offered a proven product that could deliver the performance that we believe we need. For us it was critically important that the system could be delivered within a challenging timeframe and we gained confidence from the fact that the product is already in use (in Metro de Madrid and Shenzhen).

“Nevertheless, we face different challenges. As well as being a much larger and older system, we have mixed operations such as a shared network with Chiltern Railways and London Overground. It is a complex layout, with junctions – interfacing with the Jubilee and Piccadilly lines. There are, however, similarities, for example, this is a brownfield site and we are reliant on night closure times to test and install the system.”

Measuring success

The project team’s objective is to introduce the full performance of the sub-surface signalling upgrade with minimal closures. Whilst closures will be needed to remodel the key trackwork, disruption to customers will be avoided by applying the fundamental principle of proving the system performance and reliability off-site, both in the factory and at the test track at Old Dalby, before installing it on the railway.

Carrying out testing over the next 18 months at the dedicated 5km Old Dalby test track, near Melton Mowbray in Leicestershire, will ensure that the CITYFLO 650 system completely meets all of London Underground’s requirements. Long term, this will minimise disruption to customers both by reducing the need for closures as well as by proving the reliability and performance before installing on SSR.

“Our objective is to guarantee reliable service on the railway,” Matthew Steele commented. “We will know we have been successful if there is no discernible impact of the upgrade to our customers and when we complete a system that delivers reliability, performance and the customer benefits including the increase in capacity that we defined. We recognise this is no mean feat but we are embracing this challenge to delivery on time and realise the benefit for London.”



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