Wednesday, November 2, 2011

On Favored Quarters, Off-Center Skyscraper Districts, and Poverty

by Stephen Smith

Following up on my post yesterday skyscrapers in Europe, I’d like to explain why, in detail, central business districts are generally superior to off-center ones like La Défense outside Paris or Washington’s Virginia suburbs. It’s not that I just enjoy the spatial symmetry and organic shape of a centralized city – it’s actually more efficient! Neglect it, and you’re doing a disservice to your poorest citizens, who too often find themselves out of commuting range of many of a city’s jobs.
Mathematically, there is a simple explanation derived from the equation for a circle: area = πr² – that is, the area varies with the square of the radius. Assuming you can travel in a straight line from work to home, then as the urban circle grows, the average distance between any two random points will expand with the square of the radius, since it varies in relation to area. The average distance from any random point and the center, however, will only vary with the radius. All of which is to say: As a city or metropolitan area gets bigger, the distance between any two random points rises faster than the distance between any one random point and the center of the city.
And then obviously a true city is limited by the fact that you cannot travel in a straight line from work to home on a mass transit system that’s already centered around downtown.

Tokyo from yokohama, photo by Stripy T-Shirt

more about urban form:

Urban Sprawl and Atlanta’s Air Quality Problems

Spatial Planning, Urban Form and Sustainable Transport: An Introduction

New Directions for Urban Economic Models of Land Use Change: Incorporating Spatial Heterogeneity and Transitional Dynamics

Inequality and Urban Shrinkage: A Close Relationship in Latin America

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