Tuesday, December 18, 2012

Cities and dreamers

I recently cited Alain Bertaud's new paper ("The costs of Utopia, Brasilia, Johannesburg, Moscow").  It's provocative and interesting.

Introducing economists' monocentric model of cities, Bertaud notes (p. 5), "The work of Alonso, Muth and Mills made an important -- but often overlooked -- contribution to urban planning: it demonstrated that the spatial structure of many cities is generated by a self-organizing principle driven by economic forces." 

Yes and no. Cities have changed to the point where the original model is no longer relevant.  Why? Automobiles and traffic congestion externalities have made the model as well as the actual monocentric cities untenable. But the polycentric form that Bertaud writes about was not planned but also came about via a self-organizing principle; it was driven by market forces. In fact, polycentricity is now widespread and obvious. The challenge of defining and identifying urban subcenters is now grist for urban researchers with enough patience and data.

Traffic externalities did not create traffic doomsday ("gridlock"); rather, they prompted land market responses to forestall doomsday.  The remarkable stability of average commuting travel times has been cited by many researchers.  A stronger test of spatial self-organization is the related finding that travel time stability extends to non-work travel also.  The complex land use arrangements that make this possible cannot be planned top-down.

Bertaud sees market forces trumping the efforts of designers. "Haussman did design street patterns in ninteenth century Paris, so did L'Enfant in Washington.  However, these 'urbanists' only designed the boundaries between public and private use ... they did not decide who was going to live where, they did not decide where offices and residential areas will be located and what should be the density in these urban areas. Market forces were left free to fill the bulk volumes alloacted to private use." 

Of course.  There is enough labor and capital mobility in the world so that any traffic doomsday city settings cannot compete.

On this theme, Bertaud studies the "utopian" cities and finds that their dispersion (as he defines it) is the most extreme. 

Likewise, Ed Glaeser writes on Oscar Niemeyer's passing: "Brasilia's hubris is a warning to urban dreamers ... The structures in this artificial capital are impressive, yet few want to walk its barren streets."


I should have been clear.  Dispersion by itself is neither a positive nor a negative.  "Good" dispersion is a land market accommodation that keeps travel distances in check; "bad" dispersion does not manage this. The median commute in spread out  Tokyo is 46 minutes (their mean would be longer), which is considerably longer than U.S. average commuting times.