Nigel Wordsworth reports…
Our iconic mainline termini are enjoying a rejuvenation. And many of the millions being bestowed upon them are rising up to the structures above their tracks. Paddington’s roof is being completely refurbished; so too is one half of Victoria’s. Edinburgh Waverley is enjoying a rebuild and reglaze. And as for King’s Cross – that is also having a new roof. But in its case, much more is being done. A major redevelopment is taking shape.
King’s Cross Station was opened in 1852 – built on the site of a former smallpox and fever hospital to a design by Lewis Cubitt. The station – with an apostrophe – and the surrounding area of Kings Cross – without one – were named after a 60-foot high monument to King George IV that was erected at the centre of a six-road junction. It came down in 1845.
As originally built, the station had only two platforms. All trains departed from the western platform, now platform 8, and arrived at the eastern platform – platform 1. In between were several storage roads. Departing passengers entered the station on the western side through the integral office block, the Western Range. Arriving passengers could take a hansom cab which would be waiting in the covered cab road on the ground floor of the eastern office – Eastern Range – adjacent to the arrival platform. In front of the station was a large open space.
Over the years more platforms were added and the space in front of the station became cluttered with an assortment of buildings including a Leslie Green designed oxblood-tiled underground station for what became the Piccadilly Line. A second station, housing platforms 9 to 11, was also built to serve the suburban lines.
The next big change was in 1972 when British Rail got ‘temporary’ planning permission to tear down the buildings in front of the station and construct a new main entrance/foyer. This is very bland and almost completely hides the original façade. Over the years, the temporary nature of this southern concourse was largely forgotten and passengers became used to it as it was.
However, as passenger numbers have risen, the southern concourse is struggling to cope. Today 42.5 million travellers use the station every year and predictions are that it will rise to 52.5 million in the foreseeable future. Something had to be done whilst, at the same time, addressing the problem of Camden Council’s planning permission only being temporary. In addition, the surrounding area is being redeveloped. 67 acres of brown-field site are being transformed into 8 million square feet of mixed-use properties including offices, homes and a university.
So a bold plan was fostered to tackle existing problems and make the station fit in with its new surroundings. The southern concourse will be demolished and the open space reinstated, opening up views of the original frontage. King’s Cross is one of only five Grade I listed stations – the others being St Pancras, Paddington, Huddersfield and Bristol Temple Meads – so there is a strong heritage case for this approach.
To replace the concourse, a large glazed canopy will be erected to the west of the station, between the Western Range and the Great Northern Hotel. Both these buildings will also be restored – the former for offices and the latter to become a hotel once again. The Western Range’s bomb damage, wreaked during World War II, will command attention. Meanwhile on the Eastern Range’s ground floor, the cab road was earmarked as an extra platform, named Platform 0 so as not to impact on the existing numbering.
In the station itself, platforms 5-8 are to be shortened at the buffers end to make them the same length as platforms 1-4, maximising public space inside the original building. The roofs of the two barrels will be renovated. The original timber frames had been replaced with wrought iron in the 1870s but this now needs attention. A central underground service area will be built to take deliveries, house the on-train catering operation and support the station’s retail activities.
In total, the work was divided up into seven packages. The refurbishment of the Eastern Range offices is already complete – a project recognised at the recent Network Rail Partnership Awards – whilst May 2010 saw the cab road’s conversion into a new platform, completing package 1.
Kier Rail is refurbishing the roof under package 2. It has come up with an ingenious approach in that the scaffold/crash deck is mounted on rails fixed horizontally along each barrel. Its sections are made from welded aluminium extrusion and hang from triangular trusses. As work is completed on a section of roof, the scaffold is simply pushed along to the next. This removes the need to either have an all-encompassing scaffold or to dismantle and reassemble sections as work progresses. This method should be much quicker and cause less disruption.
As the roof is reglazed, the centre will be fitted with photovoltaic cells which will provide around 10% of the station’s power requirements.
Package 3 is led by VINCI Construction UK Limited which is responsible for refurbishing the station interior. The platform end adjustments will be undertaken, along with the installation of access equipment such as lifts and escalators. Vinci is also handling the underground plant room and shared service yard (package 4). This is a road-vehicle ramp leading down into the bowels of the station, with service lifts up to concourse level.
When we visited this area, there was a half-height wall built across the main access road which had to be overcome by ladders. This apparently purposeless structure was flood protection for the Underground! With the ramps and access road half built, there is a remote possibility that a heavy downpour could deluge the new works and that has to be prevented from pouring into the Tube tunnels. The new service area connects to the Underground, giving passengers an emergency escape route and allowing for interconnecting services.
To support this underground complex which encompasses two floors, 55-metre deep piles are spanned by 4-metre thick concrete beams. This looks like massive over-engineering until you understand that the developer of the adjacent area, Argent, will be building a seven-storey 57,000 square feet building over the top of it. Spoil from the excavations was used to construct a golf course in Northolt.
With all the new construction and underground work, diversion of critical services is a package in its own right – McNicholas has been entrusted with this. Design assistance comes from Arup who are working on a number of packages simultaneously.
The most obvious part of the new development is package 6. This covers the construction of the new western concourse and refurbishment of the Western Range offices. When the latter succumbed to a bomb in the Second World War, a section towards the middle of the building was taken out. More recently the Underground needed a ventilation shaft which was driven up through this area. Now the gap is being filled in to match the original building.
The new western concourse is a steel-lattice structure with a partially glazed roof that covers the entire area between the Great Northern Hotel and the Western Range. There will also be a mezzanine floor with retail units and easy access into the station at that level, allowing passengers to cross the tracks on a bridge before descending to their chosen platform. The steel framework will be adjacent to the Grade I listed Western Range but will not be fixed to it so won’t impact upon the historic building.
There will also be access from the concourse into the station at ground level through the front of the Western Range. This was the entrance for the original 1852 station and, once existing retail units have been removed, will be again. Access to platforms 9-11 (and 9¾ for Harry Potter) is also at ground level, at the northern end of the concourse.
The ground floor of the Great Northern Hotel has been converted into an arcade giving access to the concourse. Although not part of the King’s Cross Station redevelopment, the hotel is being worked on by Argent as part of the area regeneration scheme and remains an important station access.
Work is underway on six of the packages. The plan is for these to be complete in time for the 2012 Olympics. Both the old and new concourses will be in operation for the Games, following which the southern concourse will be demolished and the resulting open space laid out. For the first time in 40 years, Londoners and the travelling public will be able to see Lewis Cubitt’s design for King’s Cross’ southern face.
Package 6 temporary works
Tony Gee has been carrying out a number of temporary works designs at King’s Cross as part of the redevelopment currently underway for VINCI Construction UK Limited. These have included enclosed pedestrian access routes through the new western concourse building, piling platforms and checks on the many buried structures for construction plant loading.
The redevelopment works also involve extensive modifications to the Western Range Building (WRB). As part of these, the southern wing ground floor structure is to be remodelled to allow the free flow of passengers from the new western concourse to the platforms. The building was constructed as part of the original station and is Grade I listed, containing many period features that are to be preserved. Tony Gee was employed to undertake the Form A concept design for this and other areas of the WRB where sympathetic consideration of the existing structure was required.
The WRB’s southern wing is a three-storey structure with a timber-framed gable roof and load bearing masonry walls. The eastern façade supports the main train shed arch roof. The works involved removing those existing walls at ground floor level and replacing them with an open reinforced concrete frame. Stability of the building and the main train shed roof had to be maintained at all times and deflections controlled to prevent damage to the historic fabric. To further complicate matters, architectural features such as staircases and stone slab flooring had to be preserved.
The developed scheme involved a series of steel trestles extending into the basement that provided temporary support to the walls and arch roof. Hydraulic cylinders were incorporated to control deflections and prevent cracking of the building. The design and construction sequence was prepared in consultation with English Heritage to ensure important architectural features were adequately protected or removed for later reinstatement.
Reproduced from our sister publication: the rail engineer magazine.