Monday, 09 February 2015 07:41

Shaping Metropolitan Growth

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Metropolitan growth receives less attention than it deserves. The spread of metropolitan regions is one of the defining features of the age, yet as most of it is taking place in the developing world it goes largely unremarked by Western planners and urbanists. Of course, we have our own metropolitan regions that are deeply problematic in terms of governance and equity. However, the overcrowded commuter trains, chronic congestion, widening rich-poor gap and rampant housing shortages have become so commonplace that few commentators connect them into a narrative of metropolitanisation. Thus a new book,  The Art of Shaping the Metropolis by the World Bank’s Senior Urban Planner is a welcome event.SPEL004

Pedro Ortiz  was Deputy Mayor of Madrid and Director General for Metropolitan Planning at Madrid’s Regional Government. During that time he led the work on the 1996 Madrid Regional Plan. His current book is an elaboration of the methods developed in that plan so that they can have wider applicability.

Geometry and the city

In The City of Tomorrow Le Corbusier wrote “The city of today is dying because it is not constructed geometrically.” Ortiz is a product of that architectural tradition that draws strongly on geometry to inform strategic urban planning. However, as he makes abundantly clear, far from dying, the city of today is growing rapidly.

The book reminds readers of the pace and scale of today’s urban spread. In 2012 there were more than 220 urban areas with populations of over 2 million, many experiencing population growth of over 5% per annum, a rate that doubles the numbers every 14 years. As Ortiz tellingly observes, most of these cities will expand as much in the next 15 years as they have in the previous 400 years.

He also makes a point that I have made in these blogs before, that because economic growth (not just natural increase and migration) is a key force in such cities, we see the decreasing population densities accompany rapid metropolitan growth.

Ortiz observes that “The lives of many millions of people for many generations will be affected, for good or ill, by the actions urban planners and administrators are taking today”. What should planners do?

Scales and grids

“The essence of physical planning is making scales compatible” says the book. The scales span a range from 1:50,000,000 (geopolitics, multilateral institutions) through the continental and then national to the metropolitan (1:50,000) then urban (1:5,000), urban design (1:500) to the architectural (1:50).

A grid form offers planners a basic and efficient and equitable way of organising urban space. Yet now for the first time planners have to work with a grid interval of 5 kms, ten times larger than their baroque predecessors used. However, to make scales compatible, decision makers must have competence at the scales above and below the one at which they routinely work.

Circles bad, grids good – why polycentric development is needed

Ortiz’ geometric analysis reveals the superiority of the grid to the circle. He is fond of argument by analogy, and so the contrast can be presented as that between a dart board and a chess board. In the dart board everyone aims for the bull’s eye: in the concentric city, the city centre commands a premium because of its superior accessibility. In contrast the matrix on the chess board allows many more moves and opportunities, bringing multiple possibilities in a relational space.

Thus the concentric city widens the rich/poor divide, the road to “discontent and social unrest”, so ultimately it is not a sustainable form. Polycentric structures break down such dichotomies. A grid makes land affordable and transport accessible.

Following this logic, Ortiz is also dismissive of New Towns. Expanding from an existing urban area is more efficient and more equitable, and enables new residents to feed on the pre-existing sense of place.

Balanced Urban Development (BUD)

The grid then defines a matrix of and for infrastructure networks. Within this net can be fitted the other urban subsystems – “housing, productive, and social”. However, the “gray infrastructure” (sic) of roads and pipes etc. must avoid ecological damage and not degrade the green infrastructure corridors. The houses and economic and social activities can then be located around the hubs in the networks.

The BUD model is then advocated as a “prototype for good metropolitan planning”. It is a guide to filling in the grid squares, which can be adapted to the specificities of different places. In the idealised model there is a commuter train station at the centre of the square, by the “historic nucleus”. Adjacent to this new housing is built, along with social facilities and “new developments”. Meanwhile, the square is bounded by environmental corridors beyond the primary and secondary road networks, along which there are industrial and “entrepreneurial production locations”.

For financial stability each commuter rail line needs to serve a population of at east 300,000, and each station a minimum of 30,000 within 20 minutes walking time. In high density metropolises stations will be 2.5km apart, and lines about 5km apart. However, subsidy is still likely to be needed.


Of course governance is a fundamental concern in planning metropolitan growth. Ortiz argues that metropolitan planning needs to offer a long term vision of how the different urban elements fit together, without trying to set out the exact details. It does not consider programming or budgets. Metropolitan planners cannot impose their will, the need to build consensus. Arguing by analogy once more, Ortiz speaks of a “tripod”, where environmental sustainability, social equity, economic efficiency are the legs and governance the seat that connects them. “Integration” is the key.


Ortiz explains how this approach was used in the 1996 Madrid Regional Plan, and how it is being adapted and applied now in many rapidly growing metropolitan areas in Latin America, Asia, Africa and the Middle East. The logic of capitalising on the flexibility of a transport grid in situations where growth is rapid is clear. To planners from a social science background, or whose practice is rooted in interpretation of the nuances of “policy guidance” from central government and micro-political alignments to deflect growth, the idea of geometry as the definitive basis for a long term plan may be unfamiliar, even unsettling.

However, Ortiz is trying to address a situation where metropolitanisation is occurring at pace in situations where there is little planning capacity to manage it. The basic ideas he propounds are broadly accepted – transit-oriented development around interchanges, a hierarchical road network, environmental conservation, an understanding of topography and the grain and structure of an urban area, and the need for an integrated approach that looks beyond the next election. Above all he is sending the message that there needs to be engagement at the metropolitan region scale, something that most governments have not yet grasped, still less acted on, while the UK government has rejected such a proposition.

There are also weaknesses in Ortiz’ approach. He admits that commuter railway networks by their nature tend to focus on city centres, but makes them an exception to his grid rule because other modes of transport are needed to serve them. More fundamentally, proximity is not the only barrier to be negotiated by the poor seeking to access to services and opportunities of a metropolis. He notes the problem of “uncontrolled activities springing up along roads and (undeveloped) infrastructure rights of way”. He sees this as imperilling the long-term economic success of cities. Yet there is a counter argument that informal trading along such routes is a key source of income for poor households and provides important economic opportunities for women .

With Joan Clos now Executive Director of UN-Habitat, and Pedro Ortiz in a key planning position for the World Bank, we have two men whose planning culture was shaped by this geometry-inspired Spanish urbanism in posts that are highly influential globally. Planners from an Anglo-Saxon tradition, charmed by curves and wavy lines of lanes traversing a landscape, distrustful of structures, forgetful of the mathematics from distant school days, but well-versed in treating each case on its merits, should reflect critically on the relative merits of these different ways of practising planning.

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