Allies and Morrison: Keybridge, Vauxhall – ADC

The recently redeveloped Keybridge estate is at the edge of one of inner London’s largest areas of laissez-faire redevelopment, where a shocking scale of dystopian building, with high-rise residential towers and perimeter blocks, extends on a ribbon of industrial land adjacent to the Thames’ south bank, from Battersea to Vauxhall. Typically, the site has an absence of urban planning, and is segregated by transport infrastructures from the existing adjacent neighbourhood on the other side of the tracks. The two areas are worlds apart. On its other sides, Keybridge is surrounded by indigenous local communities, with a heterogeneous mix of buildings of different eras and diverse types – housing, shops, warehouses, schools – with a public park.

Local Vauxhall, altered by different periods and development ideologies, has evolved into a collage of layers, experienced as the dynamic city of the walker, constantly changing from different perspectives. Keybridge is at a junction of the two city visions: the new generically redeveloped on a tabula rasa, and the incrementally altered old environment.

Adopting the idea of the collaged city, Allies and Morrison’s mixed-use, residential led project, answers the dilemma of redeveloping at a much-needed higher density, with a richly complex solution. The new Keybridge is a microcosm of the well-formed connected city, reconciling the two urban conditions it straddles: the new, where high-rise perimeter blocks and tall towers have largely been configured as objects on open sites, and the old, formed from interdependent building mass and exterior space, with overlain morphologies.

The 1.19 hectare Keybridge site previously housed a vast 1960s BT telephone exchange that was detached from its context by an over-scaled main building with a tower block covering most of the site. The northwest boundary abuts the train viaduct, with the new generic residential towers beyond. It is surrounded on its other boundaries by 19th-century buildings that jostle with 20th-century infills. Opposite the site to the east, a builder’s warehouse fractures the street line between a Georgian house and a red brick Victorian mansion block.

Responding to its mixed context, the project consists of almost 600 residential units in one- to three-bedroom ‘houses’, maisonettes or flats, which, at a density of 500 dwellings per hectare, is at the top of the London scale, with retail, commercial and workshop units, and a school.

The predominantly brick-faced development is composed of a low-rise housing terrace, two medium-rise eight storey aggregated mansion blocks, and three residential towers. Whilst ostensibly composed of three building types, these are assembled into a distinctive hybrid whole, unified by its homogenised material. Their typological readings change based on differently distanced views and layerings of scales. The distinctions between blocks are rendered less obvious at closer proximity, where the towers are stepped down to interconnected bases, making ensembles with the lower mansion-form buildings, with dedicated terraces to the duplex flats on their extruded levels delineating public and private layers. The lower blocks are composed with the scheme’s public open space, which covers one-third of the site. Keybridge is strikingly dense, whilst entirely open and permeable at ground level.

The surrounding patchwork of block types and spatial configurations did not offer an obvious or conventional grid to reproduce. Without urban configurational rules or compositional orthodoxy, Allies and Morrison has developed its own hybrid morphology for the scheme’s arrangement and the building massings, reinstating the figure-ground form of urban design. The result is a non-formalist, contextualised response to the site’s disparate surroundings and scales. Eschewing a convention to adhere to the site’s street lines, the lower buildings and tower bases are presented as folded plan forms, generated in response to parts of the immediate ground context, and the collaged environment above. Their continuous street frontages, constituted by their entrances and openings, establish the ground as collective public space in which to dignify dense urban living.

In an extended pedestrianised street scene, dependent on the blocks’ close but angled proximities, the public open space meanders through the complex, interrupted by landscape devices providing the ground-floor residences with privacy. Its permeability creates gaps between the buildings, reducing their bulk and framing outward views.

In a contemporary reading of Camillo Sitte, the composition is derived from the experience of walking, with the backdrop of mixed buildings at different heights and distances – Victorian blocks, listed buildings, banal warehouses – all treated as a picturesque composition. On the northeast corner, the new buildings, inflected in response to St Anne and All Saints Church, form a square open to the street, visible from Vauxhall Park. The folded forms have also enabled the architects to break the bulk of the more homogenised mansion house façades on the main road. The side street, Wyvil Road, is the exception, where the low-rise maisonette block adheres to the building line to reinstate a terrace, to which the Vauxhall Griffin Pub is re-attached.

The project’s modelling adapts the building components to the site’s multiple local contingencies. The new mansion blocks on South Lambeth Road, with two lower floors of retail and office units, reinforce the main street’s status. The folded forms have simultaneously led the architects to group the three residential towers into an ensemble on the more hostile north west. Along the viaduct edge, the lower-ground floor is occupied by workshop and potentially entertainment space. Unusually, a two-form entry primary school, required by Lambeth to expand the existing Wyvil Road Primary school opposite, sits at the base of the lowest tower, permitted as a result of the 106 negotiation.

A scenographic design method is used in the stepping and twisting of each tower, and the height variation between the three, so that they are constantly read in their dynamic urban context. While the lower 26- and 22- storey towers maintain their rectilinear forms to mediate with their more local surroundings, the tallest 36-storey tower, uses two incremental twisted steppings of its volume to relate to the church, the mansion blocks, and, in its slender upper form, to the more distant high-rise context.

Keybridge’s predominant red brick distinguishes the new development as an urban entity, and unifies it architectonically. The material is weighty and referential, making buildings of ground-bearing substance, and drawing the complex into its contexts, including the 19th-century mansion block and the viaduct, which from train level and from some street views around the site, appears as its base. The distinctive homogenisation of the whole scheme, expressed through its framed solidity and controlled window grids, presents it as a new city quarter, referencing elements of a collective urban language, ideologically part of London’s masonry city.

Its hierarchical ordering –with a base connected to its street life, solid body representing the surrounding urban fabric, and a top validating brick as the urban tower material – positions the project in the context of the early- and mid-20th-century high-rise city, predominantly Manhattan’s, with its stepped brick-faced towers meeting the ground with solid civic bases, and large plinth-and-tower public housing schemes.

The approach is also aligned to Hans Kollhoff’s more recent defence of the masonry city and brick-faced tall buildings, notably in Berlin’s Potsdamer Platz, where it contrasts with the surrounding towers. As with Kollhoff, Allies and Morrison’s solid, relatively unembellished tower forms, where the frame is expressed through the brick facing, question the validity of the curtained walled contemporary tower.

London’s need for denser inhabitation is established with the concomitant necessity to reincorporate redundant industrial sites into the city, specified in the Boroughs’ urban development plans. These bulky documents set out needs and requirements in measurables – without visualising their areas’ future in physical urban forms.

Responding to London’s acute housing shortage, the city has justified piecemeal private development without determining how it should meet the ground. In the absence of a civic vision and some rules of urban engagement, how do these schemes respond to their multiple contexts, to make civic architecture? The few exceptions are masterplans for mega-sites, configuring sites into blocks and streets with plot rules to establish collective building principles. London is nevertheless littered with smaller significant industrial sites like Keybridge.

What this unique scheme demonstrates is that density, where building proximities are tighter, can be a positive design component. It was achieved by conceiving the development as a piece of city with its own urban etiquette, privileging principles of figure-ground architecture without recourse to conventional urban block forms. Apart from its distinct presence as a city piece, its key principles are of a hierarchically composed architecture, where the civic is conceived in its configuration through a publicly permeable meandering ground space with a ‘continuous façade’, which, taken together with the density of its figure, could stand as a paradigm for urban planning.