Grandes planes: como los diagramas de planificación han dado forma a nuestras ciudades, exposición en SPUR (San Francisco Planning and Urban Research)

Vía Guardian.

Grand plans: how the simple planning diagram has shaped our cities

A new exhibition charts how these powerful abstract drawings have defined the nature of urban development

As David Cameron continues to progressively dismantle the remnants of the UK planning system, it might be comforting to look overseas, where the history of spatial planning is being celebrated. An exhibition opened this month in San Francisco that charts the visual history and influence of the planning diagram, from the radial spokes of the garden city wheel (which inspired the development of English suburbia) to the New York set-back rule (which generated the city's stepped skyscrapers).

Grand Reductions: 10 Diagrams That Changed City Planning, organised by the San Francisco Planning and Urban Research association, argues that these simple, abstract illustrations are "iconic distillations of values, policy agendas and ideologies" – persuasive weapons in the planners' arsenal.

"Planning indulges in the same world of image making that artists and advertisers do," writes Andrew Shanken, professor of architecture and urbanism at UC Berkeley. "Every plan is an act of persuasion, an argument for an alternative way of life that attempts to posit or convince an audience of that alternative."

Let's look at five diagrams that have had a lasting impact on the way our cities and countryside are shaped.

Garden Cities of To-morrow, 1902 – Ebenezer Howard's vision for a 'Group of Slumless, Smokeless Cities'

The Garden City was the vision of Ebenezer Howard, an unassuming Hansard stenographer, as an answer to the pollution and overcrowding of the industrial city. His pamphlet, Garden Cities of To-morrow, published in 1902, introduced the idea of planned and self-contained communities surrounded by greenbelt land.

Each community would be organised around a concentric pattern, with housing, industry and public parks arranged around six radial boulevards, to give everyone the best of both town and country life. Howard envisaged a cluster of several garden city satellites orbiting around the central mothership city, all connected by an efficient network of road and rail.

The garden city model was centred on a quietly radical programme of economic reform, in which cooperatives would own land and lease it to tenants, reinvesting the proceeds in public improvements. But the only garden cities to be built – Letchworth and Welwyn – abandoned the industrial and collectivist aspects, developing instead into models of cosy suburbia. Decentralised, monocultural communities, protected by swathes of greenery, turned out to be the real legacy of this particular diagram.

The Radiant City, 1935 – Le Corbusier's vision for a stratified functional grid

Le Corbusier's infamous vision of the Radiant City (La Ville Radieuse), like Howard's Garden City, was driven by a fervent desire to bring order to the messy reality of the early 20th-century city. The Swiss architect proposed to neatly stratify all urban functions into cleanly separated bands, forming a linear city based on an abstracted human form – with a head, spine, arms and legs.

The central precinct would be for housing: vast slab towers, set far apart in green space, to give residents equal access to light, air and open space. An endless park would be available to all, and even pass beneath the buildings, raised on stilt-like pilotis. These pedestrian-only superblocks would be surrounded by expressways with interchanges that eliminated crossings and intersections.

Other land uses were to be radically compartmentalised, with separate sectors devoted to offices, industry and government buildings as the grid sprawled ever outwards.

The vision of an ordered, Cartesian utopia proved highly seductive, and dictated the nature of postwar planning across Europe – much of which would succumb to the grim cocktail of underinvestment, poor estate-management and ghettoised social isolation.

Township grid, 1785 – the Public Land Survey System defined the US direction

Ever wondered why US planning, from the scale of the city block to the rigid state boundary, is so square? This innocuous-looking diagram might just hold the answer.

In 1785, Congress created the Public Land Survey System, in which three-quarters of the country's land area would ultimately be surveyed, sold and settled. The system laid a grid of 6-mile-square townships across the country's midsection, marching across mountains, valleys and rivers, each township composed of 36 one-mile-square sections.

The system was an expedient solution on several levels: it provided a fundraising mechanism for the federal government, minimised conflict over land claims and helped realise the aspiration of its sponsor, Thomas Jefferson, that the US should be a nation of small landowning farmers.

The township diagram, repeated thousands of times, established a pattern that would shape everything that followed: farmhouses stood in their square fields so villages rarely formed, while state and county borders were ruler-straight. Roads were placed along parcel boundaries, and urban development occurred in sectional increments, producing the characteristic one-mile grid of arterial streets seen today in cities such as Phoenix, Chicago and Las Vegas.

Nolli map, 1784 – the first map to depict private buildings and public open spaces

A firm architects' favourite, Giambattista Nolli's 1748 map of Rome was a major milestone in cartography. It presented the entire city to scale in plan view, as if from directly above, at a time when most urban views were imagined as imprecise bird's-eye aerial perspectives.

But its key innovation, which lives on today, was its clear separation of private built form and public open space: buildings are shaded black, while streets, squares and the interiors of churches, markets and courtyards are left white.

The effect – now a common analytical technique, known as figure-ground – reveals the characteristic pattern of streets and buildings that underlies urban form. In traditional urban patterns such as Nolli's Rome, streets and open spaces generally read as the foreground, defined and shaped like urban rooms by background buildings. Much modern architecture inverted this relationship, with buildings as foreground objects, set in background space, which tended to be poorly defined.

Beginning in the 1970s, urban designers including Colin Rowe turned to figure-ground maps to illustrate the qualities that were being lost and to make the case for reasserting traditional urban patterns.

Guide psychogéographique de Paris, 1957 – recorded Guy Debord's 'drift' through the French capital

Popular with architecture students going through that psychogeography phase, Guy Debord's remapping of Paris provided a visual manifesto for the French situationist movement. This group of radical scholars, artists and architects had grown increasingly alarmed at the rationalist urban renewal schemes of the 1950s, which razed ancient city quarters for the erection of glistening Corbusian towers.

They set out to confound and resist not only the excesses of bourgeois capitalism but also the tyranny of modernism's urban agenda. The situationists urged a different sort of resistance, one that happened through play, serendipity and by being deeply attuned to the experiential qualities of the city.

Debord's map depicts a directionless "drift" through the streets of Paris, as if to argue that the city is created through individual experience and collective memory, rather than a rigid plan imposed from above.

This newfound emphasis on the experience and memory of urban residents was part of a major reorientation of city planning away from top-down transformation and towards a more community-based approach. This emphasis on experiment and play has found a new voice in the 21st-century public realm, in the "tactical urbanism" of practices such as muf, and the recent wave of proposed temporary projects by young groups such as Practice and Assemble.