Thameslink

To succeed, major railway projects must be thoroughly and painstakingly planned. Following a protracted bidding process, contracts are let which usually prompts an intense period of activity, often involving significant change to the infrastructure. When finished, the scheme usually tends to merge into our everyday railway psyche to become the norm, complying with our everyday expectations and standards.

However, there is one project that, although it never seems to end or to merge into our psyche, still continues to amaze by nature of its complexity. It is, of course, Thameslink which started way back before privatisation.

This £6.5 billion project continues to challenge the skills and resilience of the most able railway engineers. Rail Engineer has followed this project for some time, the last article appearing last summer. A recent meeting with Chris Binns, Network Rail’s head of engineering for the project, revealed some fascinating developments since that last report.

The eyes of the world

Chris started by outlining a recent conversation with his team. In the past, the Thameslink scheme has been likened to ‘open heart surgery’, but the team didn’t agree with this analogy because the patient is asleep when such surgery takes place. The consensus was that the work is more akin to rebuilding Wembley Stadium whilst there is a football match underway, watched by a capacity crowd. Given events over Christmas and the subsequent media reaction, it is an understandable comparison.

London Bridge station, used by more than one million passengers per week, is one of a number of key focal points of the project. Many of the passengers are able to benefit from the use of the newly constructed terminating platforms, Numbers 10 to 15, as the project moves to the next stage of one of the biggest station redevelopments that the capital has ever seen.

The space below the platforms will eventually provide the station with an expansive new concourse area that will extend across the width of the station with lifts and escalators serving all 15 platforms. Costain is the principal contractor for this work, and Chris explained that the completion of all six terminating platforms allows the development of the new concourse to start with the construction of the new ticket office on the south side of the station at street level.

Concourse demolition progressing

The newly-constructed terminal platforms also give the travelling public a first glimpse of what the station will look like when finished. The concourse, however, will have to remain behind hoardings for some time before it can be appreciated by the travelling public. Demolition contractor Keltbray is now removing Platforms 9 and 8 and their supporting archways. A haulage road has to be maintained under the completed platforms until all the demolition is completed, limiting the amount of finishing work that can be carried out on the concourse area.

On the same path as Platforms 9 and 8, situated at the west end of the station, is the newly constructed Station Approach Viaduct, cast in-situ with precast beam decking. This structure, plus the additional 40-metre-long steel-decked West End Viaduct structure built by Costain, is designed to link the existing network with the new and unused 350 metre pathway which includes Borough Market viaduct. This pathway is designed to eventually carry an additional two dedicated Charing Cross tracks in 2018.

Thinking ahead

The West End Viaduct structure is supported on concrete piers founded on piled foundations that were constructed underneath the Jubilee Line ticket hall when the line was extended in the 1990s. Chris explained that all they had to do was to drill through the existing piled columns and reinforce them to comply with current standards. No additional piling was necessary or disruption to the ticket office. It just emphasises the importance of forward planning and how necessary it is to ensure that the project succeeds.

Skanska has also carried out strengthening work on three bridges between Waterloo East and London Bridge during 2014, which involved closing Charing Cross station. The work included the removal of a bridge girder to accommodate new S&C and realigned track. On an adjacent bridge, longitudinal timber beams were removed and the deck reconstructed and waterproofed. This essential work was required to help comply with Route Availability level 8 standards and to create a proposed track alignment required by the service requirement of 24 trains per hour between Blackfriars and St Pancras stations.

An even more intense period of work started on 20 December and continued for 16 days without a break, finishing on 5 January 2015. This was made possible by the suspension of the Southern and Thameslink services calling at the station. More than 1,000 engineers worked over 11,500 shifts, renewing track, signalling and power supplies. Chris was pleased to point out that no significant accidents were reported during this intense period of work. Details about the signalling installations and power supply are covered in a separate article in this edition of Rail Engineer.

Not only was a high level of safety maintained throughout this Christmas period, but the project delivery team was also busy monitoring over 320 milestones, ensuring that all the key activities were completed within the time allocated. So, although there was serious disruption to trains when the station reopened, along with much adverse publicity, this was primarily due to operational problems – getting trains through the modified and very constrained stage layout. The engineering work carried out was, in fact, completed on time and in accordance with the project plan.

New track layout

Balfour Beatty Rail carried out the S&C and plain line track renewal work. It installed 20 S&C units during the 16-day blockade and completed around 400 track welds. In addition, 45 new S&C units for the low level works units had previously been installed along with the renewal of more than 7,200 metres of plain line. The track design was standardised and installed using Kirow cranes and the tilting wagon system. The project had invested in an additional eight tilting wagons, boosting the national fleet by 33% in order to secure resources for this work and future key weekends.

From London Bridge station eastwards to Bricklayers Arms, close to Millwall football ground, the railway formation is supported
on masonry arches, metallic and brick arch structures. In order to keep loadings within acceptable limits, rather than use the large Kirow 1200 (125 tonne capacity) rail cranes, BalfourBeattyRailusedmuchlighterKirow 250 (25 tonne capacity) cranes working in tandem. To further reduce the loading, a new lightweight lifting beam was developed so that Kirow 250 cranes, lifting in tandem, now have the capacity to lift a concrete bearer FVS switch panel without using props, thus speeding up installation.

Creating space for the dive-under

The significance of much of this track reconfiguration work is that it has cleared the way for the construction of the Bermondsey dive-under. Bricklayers Arms junction, near New Cross Gate, has been remodelled, severing the Up and Down Sussex Fast lines and the Down Sussex Slow, which means that Southern’s trains to the London Bridge terminating platforms are temporarily constrained to use the three-track Bermondsey Spurs.

Also, de-construction work on Platforms 5 and 6 means that Southeastern’s Charing Cross trains will no longer stop at London Bridge station.

This arrangement is planned to last for 20 months and will be followed by similar non- stopping arrangements for the Cannon Street services when Platforms 1 to 4 at London Bridge are demolished. The reward will be a four-track dive-under for Charing Cross trains that will be able to stop at London Bridge station’s new platforms 6 to 9, and then travel over the Borough Market viaduct and on to Charing Cross. Thameslink trains will enjoy two dedicated tracks that will go over the dive-under in the same direction toward London Bridge station andthenewPlatforms4and5,butthat’sa while off yet.

Skanska is the principal contractor for the dive-under construction, which is a significant undertaking in itself. Already in 2014, using 500 and 250 tonne cranes, Skanska has lifted in tandem three large steel span sections onto four previously-constructed reinforced-concrete piers. Then, 28 precast concrete L-shaped units were fixed onto the steel structures secured by 1000 shear studs that were welded on site.

This work took place alongside the brick arched viaducts carrying six main lines. It forms the start of a transitional structure that will eventually span from the existing brick viaduct to the Bermondsey dive-under. There are around 35 arches on each of the dive-under lines that must be demolished and track slewed before the dive-under can be constructed. The plan requires Skanska to commence demolition of the arches carrying the newly-severed Up and Down Sussex Fast Lines in June, with the dive-under box to be completed in 2017.

Further afield, fitting out work in the Canal Tunnels situated between Kings Cross and St Pancras has now been completed along with the necessary track connections into the respective main line routes. Final testing will take place in 2015 but the tunnels will not go live until 2018.

Siding work and gauge clearance work to Bridge 184 at Peterborough is complete to ensure that all will be ready to receive the new Class 700 Siemens trains that are currently travelling at 100 mph on test tracks in Germany.

Retaining expertise

The longevity and complexity of this Thameslink project demands a very high level of commitment and ability from all its engineers involved. There could be a concern that this highly-skilled and very-experienced engineering team may start to get restless and look for new challenges as those associated with the Thameslink project start to ease off. Chris Binns’ response was immediate – he doesn’t want to lose that talent and experience so work is already underway to look at where the Network Rail Thameslink team can best be re- deployed afterwards.

Meanwhile there is still plenty to keep them all occupied until 2018.