IN THE SHADOW of London's tallest building, The Shard, one of the city's oldest stations is being transformed as part of a major project to massively increase north-south rail capacity in the British capital. Last year work began on five-year project to rebuild London Bridge - Britain's fourth-busiest station - which involves completely remodelling the station layout, replacing three terminus platforms with three new through platforms and building a new concourse.

The project is a core component of Network Rail's (NR) £6.5bn Thameslink Programme, which will employ ETCS and Automatic Train Operation (ATO) to provide metro frequencies on the central section of the route. But unlike the core section of the east-west Crossrail link (IRJ June 2011 p26), with which it will intersect at Farringdon in central London, Thameslink involves upgrading an existing railway, and one of the busiest railways in Britain.

The Thameslink Programme traces its origins back to 1988, when British Rail (BR) reopened the Snow Hill Tunnel beneath central London connecting the 25kV ac London St Pancras - Bedford Midland suburban lines with the 750V dc third-rail network south of the River Thames to create a north-south heavy rail link through the heart of London.

A dedicated fleet of 60 new dual-voltage class 319 EMUs was acquired to operate the route (later supplemented by a further 24 trains), and this accounted for the bulk of the capital investment in the scheme, with all necessary signalling and track work being delivered for just £4m.

Such was the early success of Thameslink that BR quickly developed plans for a massive expansion of the network, increasing the number of stations served from 50 to 169 and extending maximum train lengths from eight to 12 cars. However, BR's chosen moniker of Thameslink 2000 proved to be an overly-optimistic title as the project became mired in economic recession, the privatisation of BR, political indecision, and planning delays. It was only following a second public inquiry that the plans were finally approved in December 2006, and it was not until mid-2007 that the government finally agreed to fund the project.

The Thameslink Programme significantly extends the reach of the original Thameslink network. To the north, the project brings the Great Northern suburban lines into the system, giving Peterborough and Cambridge direct services to stations in central London and southern England. South of the River Thames, the network will be expanded to serve a variety of destinations in the southeast. Accommodating the new trains will require platform extensions at a number of stations, track and signalling alterations, and modifications to a number of depots and stabling points to accommodate longer trains. Power supplies and telecommunications systems are also being upgraded.

The first part of the project to be completed was the new underground station at St Pancras International, which opened in December 2007.

This was built as part of the redevelopment of St Pancras for international high-speed services, and replaced the existing Kings Cross Thameslink station.

The Thameslink Programme is divided into three phases, which NR refers to as Key Output (KO) stages. KO0 involved upgrading the core section to permit the operation of up to 15 eight-car trains per hour (tph) between St Pancras and Blackfriars. The Moorgate branch closed to allow the extension of platforms at Farringdon, which will become a key hub in London's railway network as an interchange between Thameslink, Crossrail, and London Underground's Circle, Hammersmith & City and Metropolitan lines.

The £2bn KO1 was completed last year and increased peak capacity on the core section of the route to 16tph. With the completion of platform lengthening works, including Blackfriars and Farringdon, this phase of the project saw the introduction of 12-car trains between Brighton and Bedford in December 2011.

The three-year £500m project to reconstruct Blackfriars station involved extending the through platforms across Blackfriars Bridge, with the construction of a new entrance on the south bank of the River Thames. A new roof was constructed across the platforms and this is equipped with 4400 solar panels, which will generate 900,000kwh of energy per year for use at the station.

KO1 had to meet its deadline for completion because work on the Thameslink Programme would be reduced for the duration of the 2012 summer Olympics and Paralympics, which were hosted by London between July and September that year.

Third phase

Launched last year, KO2 is the third and final phase of the project and is also the most ambitious, representing a total investment of £2.4bn. "KO2 really opens up the core of the railway," says Mr Chris Drabble, NR senior sponsor for the Thameslink Programme. "The completion of the link with the East Coast Main Line (ECML) is a significant part of what enables the benefits of the project to come through."

During the rebuilding of St Pancras station and the construction of the Channel Tunnel Rail Link, the opportunity was taken to build a 600m twin-bore tunnel between St Pancras and Belle Isle Junction, north of King's Cross. As part of KO2 the so-called Canal Tunnels will be fitted out and linked to the core section of Thameslink and the ECML, which will enable the operation of through services from Cambridge and Peterborough to destinationa south of London for the first time.

With the opening of the Canal Tunnels in 2018, peak capacity on the core section of Thameslink will be stepped up again to 20tph.

London-Bridge-aerialAnother important element of KO2 is the rebuilding of London Bridge station. This involves replacing all track and platforms, as well as a new station concourse at street level, which will be the largest under-track concourse in Britain. The station will have six terminating platforms and nine through platforms, and will be served by up to 18 Thameslink services per hour at peak times, as well as trains from Charing Cross and Canon Street to the southeast, and from the terminating platforms to the south of England. The project will increase passenger capacity at London Bridge by 66%.

The challenge at these constrained city centre locations is the need to accommodate not only the busy railway running through the site but also the city that surrounds it. "London Bridge's concourse is 150m long and 80m wide, and the platforms are supported on 20m-long steel beams," Drabble says. "A major challenge for us is how you bring these materials into the heart of London without bringing the city to a standstill. We've learnt lessons from previous major projects such as the West Coast Route Modernisation and we're passing on our experience to other projects."

Reconstruction work at London Bridge will move to the upper level through platforms from January 2015 to January 2018, requiring the diversion of all Thameslink services via Elephant & Castle and Herne Hill. When Thameslink is fully operational, currently up to six trains per hour will continue to serve Elephant & Castle.

Drabble says that in addition to completely rebuilding the station, the upgrading of London Bridge will involve "one of NR's biggest-ever signalling projects." In 2011 NR awarded Invensys Rail (now Siemens Rail Automation) a framework contract to design, test, commission and install signalling systems for the core section of Thameslink, including ATO and ETCS which will be overlaid in the core and part of the London Bridge area to enable automatic control of all train movements. This will enable the Thameslink core to operate at its peak design capacity of 24 trains per hour per direction from 2018, which together with the introduction of the new train fleet will increase the number of peak-hour seats on the core section by 80%.

Flat junctions on the intensively-worked commuter network in south London are a major obstacle to increasing capacity, and tackling these bottlenecks has been a priority for the Thameslink Programme. A key project in KO2 is the Bermondsey dive under, which will minimise conflicting movements on the eastern approach to London Bridge between Thameslink services and trains from Charing Cross and Canon Street to the southeast. On the London Bridge - Lewisham line, a second bidirectional track has been constructed on the Tanners Hill flydown between Tanners Hill Junction and Lewisham Vale Junction, and this was commissioned last year.

Drabble stresses that building a 24tph railway is as much about station design as trains and signalling. "We will be running 2.5 minute headways and dwell times will be about a minute, so how passengers interact with the system will be vital to running our full hourly capacity in the core," he says. "All of our major stations are designed from the ground up around how people move and interact with the station. If you channel people through fixed routes there is a potential that there will be delays, so the whole philosophy has been to disperse passengers. London Bridge has five main entrances, and escalators are situated in the middle third of the platform area, which means it's less than a 100m walk to any part of the train. This means passengers are distributed evenly along the length of the platform, minimising dwell times."

Accessibility for passengers with reduced mobility (PRM) has been another key consideration. For example, core area stations are equipped with clearly marked high-platform areas to reduce the step height between the platform and the train. "PRM really drives the ethos of how we design stations, and we believe it makes our stations work better overall because it makes them more accessible for all passengers," Drabble says.

Mega franchise

As the Thameslink Programme moves towards completion, the franchise map in southeast England will be redrawn to reflect the impact of the project on the operation of the region's railway network. A new Thameslink, Southern and Great Northern (TSGN) franchise, which will be the largest passenger franchise in Britain, is currently being tendered and will encompass Thameslink/Great Northern (TGN), currently operated by First Capital Connect (FCC) and South Central, which is currently in the hands of Southern, a partnership between Govia and Go-Ahead. It will also include some services currently run jointly by FCC and Southeastern.

The seven-year franchise will begin in September when it will take over TGN services from FCC. Most services jointly operated by FCC and Southeastern will transfer to the new TSGN franchise in December, although some will return to Southeastern. In July 2015 TSGN will take over Southern services with the expiry of the current South Central franchise.

Services will be operated by a purpose-built fleet of Siemens class 700 EMUs (see below), but delays in concluding the PPP contract between the Department for Transport and the Cross London Trains consortium means that compromises have been required to compensate for late delivery of the fleet. FCC's fleet of 86 class 319 EMUs is supplemented by 26 class 377 sets, which provide sufficient capacity to cover current requirements, and FCC will receive further class 377/2s from Southern in the next few months. This will allow the transfer of some class 319s for use on newly-electrified routes in northwest England, where EMUs are urgently needed for the start of Manchester - Liverpool electric services in December.

Southern has ordered 29 four-car class 387 EMUs from Bombardier, which will be used on Thameslink services prior to the arrival of the class 700s, releasing class 319s for redeployment on other routes. The class 387s will later be transferred to other operators when the Siemens trains are available for service in sufficient numbers.

Drabble suggests that one of the successes of Thameslink is that the project generates comparatively little media coverage because it has successfully kept a busy railway running reliably through the middle of a vast and complex construction site. To some extent it has also been overshadowed by its east-west counterpart Crossrail, a new-build railway and one of the largest construction projects in Europe. But as an upgrade on a truly grand scale, Thameslink has a compelling story to tell.

New trains: the class 700 fleet

IN June 2013 Siemens signed one of its largest-ever rolling stock deals when it was awarded a £1.6bn PPP contract by Britain's Department for Transport (DfT) to deliver 1140 class 700 Desiro City EMU cars for Thameslink.

Siemens is a member of the Cross London Trains (CLT) consortium, which includes financial partners Siemens Project Ventures, Innisfree, and 3i Infrastructure. CLT is responsible for financing, supplying and maintaining the trains, and the PPP contract is based on train availability, with the consortium incurring financial penalties if it is unable to provide the specified number of trains for service.

Siemens has spent £80 million designing and developing the Desiro City, which although derived from the earlier Desiro UK range, is around 25% lighter, has better performance and uses entirely new bogies which have already undergone dynamic testing in Germany.

The fleet of 115 dual-voltage (750V dc/25kV ac) 160km/h EMUs will be supplied as 55 12-car sets, each seating up to 666 passengers, and 60 eight-car trains, which will seat 427.

Production is already well underway at Siemens' Krefeld facility in Germany, and the first trains have now been formed for static testing. Two completed vehicles are currently at the Rail Tec Arsenal climatic testing facility in Vienna.

CLT will lease the trains, initially to FirstGroup and subsequently to future operators of the Thameslink franchise.

The lease agreement calls for very high availability from the new fleet with 110 daily diagrams for the trains in 2019 (from a fleet of 115) with 107 in scheduled service and three eight-car reserve trains to cover for failures or disruption.

Two new depots are being built to maintain the fleet, one in north London at Hornsey and the other larger depot at Three Bridges on the London - Brighton line.

The first train is due to arrive in Britain in August 2015 and it will be based at Three Bridges for final testing on the Brighton - Bedford route. The first units will be formally handed over to First Capital Connect (FCC) on December 18 2015 for staff training, before entering passenger service in spring 2016.

The class 700s will feature 2+2 seating in both standard and first class. Real-time passenger information systems will communicate information on the route and journey as well as real time information on connecting train services.

As the trains will only have cabs at the outer ends and full-width gangways there is substantially more space available for passengers than on the existing trains. The maximum passenger loading, including standing passengers, is 1754 for a twelve car-train and 1146 for an eight-car set.

Network Rail has worked closely with Siemens and train operator FCC in order to integrate the development of the class 700 with Thameslink infrastructure.