St Pancras Station, hotel and surrounding 50 hectares of railway lands are soon to see some of the most important regeneration work in London for years, thanks to the arrival of the Channel Tunnel Rail Link.
Representing the culmination of over a decade of work on the project, St Pancras will by 2007 be the project's end point - for many future passengers their final destination, for others their link into London's and the UK's transport networks.
The station will be transformed into one of the country's main railway hubs, providing not only six international Eurostar platforms but also three domestic platforms for new high speed train services from Kent - plus Thameslink, Midland Main Line (MML) and Underground services. A new Heathrow Express service is also being planned.
However, to fit the 425m long Eurostar trains, it was obvious Rail Link Engineering (RLE) would have to radically redesign the existing St Pancras station.
By 2007 the station will be more than double the length of Victorian engineer William Barlow's train shed - with the addition of a horizontal roof extension made of aluminiumclad louvre blades and glass. A 22m by 110m glass atrium will connect the two very different structures, at the heart of the new station.
'It's old meets new, unashamedly, ' admits lead architect Alastair Lansley. 'The new shed isn't designed to replicate Barlow.'
The station extension will be built on the northern end of the existing shed, stretching more than 300m up towards the Regent's Canal. The new roof will cover much of its length; its 240m long steel structure rising 20m above street level. It is wider than the existing train shed so it can accommodate the increased number of platforms.
'It's like a huge table top straddling the railway with seven legs on each side, ' says Lansley.
The 13 new platforms beneath will serve the existing MML, and domestic and Eurostar services.
The louvred roof is designed to allow MML train diesel fumes out and fresh air in.
Only clean-running Eurostar trains will come to halt underneath Barlow's roof. 'That way we won't subject the roof to any more diesel fumes, ' says Lansley.
This extension may cater for the trains; but what about the resulting influx of passengers?
'The international train (passenger) figures alone, at peak, are similar to Terminal 4 at Heathrow, ' says Lansley, 'But during this period, international passengers will represent only a third of the total passenger numbers in the station.'
The ticket hall and meagre waiting areas of the existing station could never have hoped to cope with these numbers. But RLE knew St Pancras held a wealth of hidden space beneath its platforms and will exploit it.
When St Pancras station was built, Barlow raised the iron plate platforms 6m above ground level because incoming tracks had to clear Regent's Canal.
Despite subsequent platform overhauls, the station remains supported by 688 iron columns on brick piers - deliberately spaced at the time of building to allow the storage of beer barrels in this street-level undercroft.
By 2007 the undercroft will be opened up to house the international arrivals and departures lounges - together with the main north-south passenger concourse, waiting areas, executive lounges, ticket halls, cafes, bars and shops.
The station extension will continue this theme, with the ground floor level beneath the platforms housing the main central concourse, domestic ticket offices, shops, station management offices, and car and bus parking. At the end of the extension there are train cleaning and replenishment facilities in a 'shorebase' just to the north of the re-routed public highway which passes under the platforms.
Departing passengers will arrive at the new main entrance to the station, situated at ground level where the eastern facade of Barlow's shed meets the new extension. International passengers have another entrance, also on the eastern facade, but further towards the front of the old station. The current main entrance off Euston Road will become part of the St Pancras Chambers Hotel redevelopment.
Once inside, domestic passengers will circulate in the concourses at street level before gaining access to the platformlevel concourses by a series of lifts and escalators. For international passengers, access to the platforms will be via inclined passenger conveyors and lifts rising up through the platforms directly from the departure lounge. The system ensures that passengers do not have to travel long distances to reach trains, or tackle several floors.
Non-travellers can also access the platform-level concourses and gain views of Barlow's old train shed, due for refurbishment as part of Contract 108/109/139; but a clear screen will prevent them from entering the international platforms.
Lansley explains that the team spent a good while researching records of Barlow's designs to ensure the refurbishment was in keeping with the original. As a result, the restored ironwork will be repainted sky blue and the roof apex refitted with glass to allow natural light into the station.
'It will give more light than is provided at Liverpool Street, ' he says.
Passengers leaving the new station will find themselves in what Lansley hopes will eventually be a new 'London space', formed by the diversion of St Pancras Road towards the east as part of C135.
A pedestrian area between King's Cross and St Pancras stations will be created as part of the redevelopment, complementing the new King's Cross station entrance which will be directly opposite.
New works to King's Cross station will also be integrated with London Underground's plans to expand the underground ticket halls to cope with the increased passenger numbers (see box).
St Pancras Road will then bisect Goods Way to the north, which will be straightened to pass through the new station extension at ground level. This is designed to give a more fluid, integrated traffic flow around and between the two stations.
Before this vision for the station can become reality, a great deal of civil engineering works must take place on the old railway lands extending 1km to the north.
The lands currently house the operational railways of the MML, Thameslink, North London Line, North London Incline and East Coast Mainline (ECML), EWS railway sidings serving concrete batching plants, the Regents Canal, several railway buildings and roads, and a series of gasholders.
The gasholders lie directly in the footprint of the station extension. Work has already begun to take them down - a task being undertaken by Edmund Nuttall as part of Contract 102.
Three of the listed Victorian wrought iron holders will be saved and put into storage.
Work also begins soon on a complex sequence of MML line diversions, initially sweeping them further to the west before entering platforms in the existing shed as part of Contract 104.
This, together with the highway diversions in Contract 135, will enable Contract 105 to concentrate initially on the eastern side of the extension to create the east deck 'interim station'.
This is due for completion in 2003.
The MML trains will then be diverted onto four new platforms in the 'interim station' leaving the old St Pancras station platforms empty. They will then be decommissioned and total refurbishment under Contract 108/109/139 can start.
At this point construction of a 0.5km long subsurface box to house a new Thameslink station will also begin, before the western side of the extension is built and the 13 platforms completed.
The new subsurface box will be built under Contract 105 as part of Railtrack's planned Thameslink 2000 project, to form Thameslink Midland Road station as an integral part of the enlarged St Pancras Station, eventually allowing the existing King's Cross Thameslink station to be taken out of service.
'The Thameslink box had to be included in the CTRL 'Area 100' works because the west deck is scheduled to be built directly over it and construction later would have been impossible', explains RLE Area 100 project manager Ian Gardner.
'Our new platforms will use it as a support, ' he says. But construction of the box around the old Thameslink tunnels running straight through the site will be a difficult job.
'We'll sink secant pile walls either side of the tunnels while the Thameslink trains are still running, ' says Gardner, 'but we'll have to close them when we come to build the base and roof.'
Northern Thameslink services will then terminate at two additional platforms in the east deck 'interim station'. Turnaround facilities will also be built at Farringdon Thameslink station for trains from the south.
However, closure for the line is limited to six months, so the whole box must be completed by September 2004. Thameslink services will then run through the empty shell, before its fit-out as a completed station.
Completion of the Thameslink box will enable work to begin on the western side of the extension, due for completion in February 2006. The west deck will then be commissioned, and MML trains diverted there permanently.
Only by December 2006, after considerable finishing work, will the whole St Pancras station - ol and new - be commissioned as one.
Throughout construction of the box and decks, work will continue to the north. Contract 104 contractors will carry on railway staging works through to installation of the final rail alignments and systems. Another major contract, 103, will build the embankments, bridges, viaducts, highways and utilities diversions necessary for the CTRL. 'The programming of this package is also challenging, ' says Gardner, 'since it involves works affecting operational Railtrack infrastructure and the relocation of the concrete batching plants without interrupting their supplies, as well as constructing two new cross-site tunnels for Thameslink from the ECML into the subsurface box.'
Gardner adds that the total amount of new track to be laid across 'Area 100' amounts to almost 20% of the total along the 39km Section Two.'
In addition to the new CTRL tracks feeding through the greatly expanded St Pancras 'throat' into the international and domestic platforms, there will be linking chords onto the North London Line (NLL) with a view to Eurostars eventually accessing the West Coast Main Line (WCML). The WCML will link St Pancras with Scotland, allowing travellers from Brussels or Paris to pass directly through St Pancras, straight on to Glasgow. Similarly, there will be new chords linking St Pancras north to the ECML for connections up to Edinburgh, and from the MML to the NLL.
'If you add it all up, it comes to about 21km, including 94 turnouts, ' Gardner explains.
'The completed project will change St Pancras from a neglected station with four trains an hour to London's major hub with in excess of 40 mainline trains an hour.'
C102 - Removal of gasholders and gas governor relocation - Edmund Nuttall - £5.15 M C103 - St Pancras Kings Cross Railway Lands Civils Works - Kier Construction and Edmund Nuttall JV - £107 M C104 - Railway staging and interface works - sub-divided into more than 10 smaller contracts.
C105 - St Pancras Station extension and interim station - still in tender process C108/109/139 - St Pancras Station refurbishment, fit out and MEP - still in tender process (packaged together as one contract) Key features: Urban regeneration, construction of a train shed and platform extensions, refurbishment works, subsurface station box construction, railway staging works, new transport interchange for the capital.