Notopia: The fall of streets in the sky9 JUNE, 2016 BY DOUGLAS MURPHYFull screen

The three-dimensional city was undoubtedly naive, but the implications of its disappearance are profound

Walk between the glassy offices and tucked-away churches of the City of London, along the thundering roads down by the Thames, and you can occasionally find staircases embedded in the sides of buildings. It’s not always clear that they’re public, but if you follow one upwards they sometimes take you to wide, deserted corridors leading along the flanks of buildings, crossing streets, and more often than not ending in truncated bridges or closed off dead ends.

These are small remaining fragments of the ‘Pedway’, a postwar scheme to create a network of elevated routes across the City that would allow pedestrians to travel anywhere without ever having to cross paths with a motor vehicle. They’re a relic of the idea – once popular, now largely discredited – of the ‘three-dimensional city’: urbanism that abandoned the primacy of the ground plane in favour of a rich spatial interplay of different layers of activity.

A century ago, as the car began to take over the streets, three-dimensional separation became part of the basic vision of the future city, visible not only in the illustrations in popular science magazines, but also the world of architectural manifestos and Modernist urban theory. Le Corbusier’s Ville Radieuse and Hilberseimer’s Vertical City both proposed a metropolis where cars streamed down massive roads while pedestrians gambolled along several storeys up, the hazards of them sharing the same space eliminated as part of the efficiencies of the modern planned city.

In 1963, a major contribution to bridging the gap between theory and reality was made by the Buchanan Report. Later published as Traffic in Towns, the report described the threat posed by rapidly rising car ownership to the UK’s safety and prosperity in apocalyptic tones. Thousands were dying on the streets, cities were grinding to a halt, and ‘if we are to have any chance of living at peace with the motor car, we shall need a different sort of city’.

Traffic in Towns set out the terms that would become familiar in the later postwar building boom: vehicle traffic was banished to the physically lowest levels, with the creation of an elevated ‘deck’ level, free from vehicles and well landscaped, linking point-like buildings interspersed through the tangle of low-level roads.

‘By the 1980s, a powerful backlash had grown against the three-dimensional city’

Of course, if it were just about avoiding problems, this approach would not have had much to catch the imagination. But it also offered a vision of a form of modernity that promised dramatic improvements in the spatial experience of the city: ‘Comprehensive development makes it possible,’ said the report, ‘to apply the techniques of multi-level design, which not only yield much-needed extra space, but open the door to the creation of new environments of the most interesting and stimulating kind.’

The Buchanan Report’s focus on urban centres coincided with the rise of a similar urban concept for housing. Britain had a long history of flats accessed from corridors running along the outside of buildings, and early 20th-century municipal housing frequently used this space-saving device. But in rejecting the rigid CIAM approach to planning, the idea of bringing traditional street-life right up to the doorsteps of elevated flats caught the imagination, and ‘Streets in the Sky’ were born.

The Smithsons’ unsuccessful Golden Lane competition of 1952 polemically described the ‘street in the air’, and they claimed that with their invention ‘a new dimension has been added to the life of the street’. The early success of their students Jack Lynn and Ivor Smith’s Park Hill, Sheffield, with its milk floats entering at ground level and ending up on the 12th floor, made the deck-access approach world renowned.

Across the UK, especially during the system-building boom of the late ’60s, deck-access blocks were built up and down the country, connecting buildings across large estates, leaping dramatically across gaps, creating a futuristic new landscape for dwelling. In New Towns such as Runcorn, long decks connected estates to shopping centres, and in comprehensively redeveloped cities such as Glasgow, or T Dan Smith’s Newcastle, vast networks of raised walkways became normal, passing through buildings, over motorways, carrying the public through the new three-dimensional city.

‘In many places the three-dimensional city still exists – in Hong Kong, famously, one

can travel for many miles without ever setting foot on the natural ground’

This enthusiasm did not last. Jane Jacobs’ paeans to street life asserted in concrete terms the qualities that the Smithsons had tried to abstract, but made a strong case that street life simply could not exist out of its basic context. Despite her writing being based on specific American examples, Jacobs touched a nerve in a UK becoming more distrustful of top-down planning, and she became a hallowed reference for those opposed to state-planning and the destruction of the historic city.

By the 1980s, a powerful backlash had grown against the three-dimensional city. In housing, the social breakdown associated with large public housing estates allowed all kinds of experts to claim they had the answers, and architecture often got the blame. Followers of Oscar Newman in the US or Alice Coleman in the UK claimed that the multiple access points that were offered by deck-access estates meant that criminals were given incentives to misdemeanour by the network of escape routes available to them.

Hysteria peaked in the UK with the Broadwater Farm riots of 1985. This estate was completely linked by elevated walkways, and the hacking to death of a policeman was seen to be the direct consequence of a gang of youths exploiting the changing levels to effect an ambush. In the aftermath of the riots the decks were all demolished.

This flattening tendency quickly spread. In the 1990s Coleman was given the chance to remake one of her most infamous case studies, the Mozart Estate in west London. Among a variety of measures she took, the extended upper level walkways were all demolished, bringing everything back to ground level and conventional streets.

‘So what was the three-dimensional city? It was undoubtedly naive, and in some ways a solution in search of a problem’

You can see it now at the Mozart and in many surviving postwar estates – truncated concrete walkways, new constructions creating closed-stair access, frequently in the apologetic Postmodernism of the John Major years. The original buildings look almost embarrassed, their vault towards the future brought crashing down to earth.

In the centre of cities a more subtle reaction took place. The pedestrian remained key, but on a firmly restored ground plane, and with a greatly reduced sense of their capabilities. Letting agents claim that leaving the ground level renders retail useless, as shoppers are disinclined to climb stairs. Outside malls, retail sticks firmly to the ground.

And the underlying problem that initiated the three-dimensional city – that of the car – has been turned on its head. The postwar attempts to make room for the automobile are now seen to have only encouraged it, and the segregated approach to traffic engineering is nowadays a mistake that everyone working in construction has to make amends for, stitching broken cities back together.

Of course, in many places the three-dimensional city still exists – in Hong Kong, famously, one can travel for many miles without ever setting foot on the natural ground. And many modern developments – such as Canary Wharf – are actually perched up on many levels of construction, yet are illusionistically decorated to appear traditional and street-like. It seems that as with so many things, the UK’s enthusiastic flirtation with modernity after the war has had to be purged from memory.

So what was the three-dimensional city? It was undoubtedly naive, and in some ways a solution in search of a problem. But the implications of its disappearance are quite sad. On the one hand, a phenomenologist might argue that humans fundamentally require a sense of ground, and should not be thrown into a spatial environment that is unfamiliar and provokes anxiety. In this reading, a vertiginous, stimulating environment that revels in its artifice is only a recipe for alienation. Strangely, this argument neatly fits the corporate Weltanschauung that only believes in ‘active frontages’ and ‘footfall’, in mixed-use housing above offices above shops, for ever and ever, amen. But both ways of understanding the city fundamentally argue that nothing can ever change.