Existing Structures, Construction and Materials

Existing Structures, Construction and Materials

King’s Cross Station Facts:

150 years old

252 metres long

92 metres wide

41 hectares of regeneration

24 stakeholders

12 platforms

6 underground lines

50 million passengers annually by 2012

£400 million investment

7000 square metres new concourse

60 seconds from St Pancras Station

Construction

King’s Cross Station’s first architect was Lewis Cubbit, he designed two round arched roofs with laminated timber beams to cover and the span was 71 feet. This was because the theory of those days was that twin platforms were used for coming and going. The façade is plain, undecorated brick: the dominant motif is the diagrammatic cross-section of the engine sheds themselves. Between the two massive arches is a 120 foot clock tower, somewhat Italianate, a more magnificent version of a device Cubitt had already employed several times in smaller Home Counties stations.

At the foot of these monumental arches was a five bay arcade. To the east a third arch covers a carriage drive, a motif reflected on the west where the structure housed offices and waiting rooms. According to The Builder in 1851 at King’s Cross the architect did not seek flamboyance, ostentation or effect, but was alone satisfied by “the largeness of some of the features, the fitness of the structure for its purpose, and a characteristic expression of that purpose”. The material used was wood because it was cheaper but less durable, but then iron was soon used to replace this.

This new design re-orientates the station to the west, creating significant operational improvements and reveals the main south façade of Lewis Cubitt’s original 1852 station. Morevoer this is the time of great advances in industrial production and in terms of construction technology alone, John McAslan and Partners has shown that King’s Cross Station exemplifies the pioneering transition from timber and masonry construction, to new visionary structures that exploited the enormous engineering potential of iron and steel − a development that itself depended on the new railway system. This enormously complex £547m redevelopment project required a series of layered interventions involving three very different areas of architectural specialism: re-use, restoration and new build.

Structure

After many years not only did the material change but also the structure and construction of Kings Cross Station changed drastically. In this scenario, the urban framework, properly conceived, becomes a complex and layered matrix of infrastructure, development, sustainability and public space. This is the new scientism of urban design, which seeks to rebalance aesthetic and thematic urban judgments with an empirical analysis of urban form, movement, environmental and energy systems.

The result is a retina of diamond cells, capable of opacity, transparency, and a widening and narrowing horizon as the curvature changes from outer rim into plunging interior funnel. As the roof converges, the pattern closes and slips down like a mantle to the station entrance, which also serves as a trellis column.

The rim of the structure orbits low, drawing in the visitor. In section, the roof is a parabolic trajectory that flares out on all sides only to be pulled down again into the central focus, a patterned screen that meets the ground, heralding the entrance into the station. The structure is supposed to express both civic aspiration and obligation. This structure is a column-free canopy with an undulating diagram-grid like frame. Weight was a major issue here. And it was the constraint of the sub-surface structural grid of the Underground’s ticket hall that suggested the fan-shaped canopy with its radial column arrangement. The station’s Main Train Shed is 250m long, 22m high and 65m wide, spanning eight platforms.

Materials

The design delivers a sense of grandeur, an almost tidal flow of materials of glass and steel – but not at the expense of human scale or the humane atmospherics of public spaces. The canopy falls gracefully from its 18m high point near the façade of the western range to a height of 6m at its perimeter. A structure of thin steel weaves intricate three-way patterns over the vault, one direction running towards the entrance, the other two spiraling diagonally, pulling against the line of that first indicator.

The restoration includes revealing the bold architecture of the original south façade, re-glazing the north and south gables and refurbishing platforms The two barrel-vaulted roofs are currently being refurbished and lined with energy-saving photo-voltaic arrays along the linear roof lanterns, while a new glass footbridge designed by JMP extends across the Main Train Shed, replacing the old mid-shed Handyside bridge and giving access to every platform as well as the mezzanine level of the concourse.

Bibliography

http://www.mcaslan.co.uk/admin/uploads/Reference/Downloads/JMPKingsCross.pdf

http://www.mcaslan.co.uk/downloads/

http://www.archdaily.com/219082/kings-cross-station-john-mcaslan-partners/

http://www.mcaslan.co.uk/projects/king-s-cross-station

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