11.522: UIS Research
Seminar (Fall 2015) - Discussion notes
Monday, October 5th, 2015, 6-8 PM
Studying the Linkage between Local Labor Markets, Urban Form and Social
Stratification
Discussion Leader: Roberto Ponce-Lopez
According to theories
of urban economics, economies of scale lie as the foundational element of
cities. Economic actors benefit from agglomerating altogether in a dense urban
space, such benefits are expressed as gains in productivity and reductions in
transportation costs. These economic and agglomerative forces are continuously shaping
the urban form through flows of people and goods traveling across local
geographies. People travel from residential locations to jobs and places of
consumption. This spatial interaction process exhibits a labor and consumer
market geographically anchored across the city. A snapshot of the spatial
layout of such markets is available by looking at census data and detailed
travel records of people and goods.
The interaction
between urban form and local markets is a two way influence. Urban form also
shapes market interactions, affecting the emergence and location of activity
centers, land consumption, and travel to places that agglomerate work and consumption.
Likewise, planners can get to affect local labor markets though their influence
on urban form. Bertaud (reading #1) claims that urban planners have three tools
at disposal to affect urban form, which are land use regulation, infrastructure
investment, and taxation.
Bertaud's reading discusses the implications of monocentric and polycentric urban forms for land consumption, housing prices, population density and travel flows. He identifies the center of activity, or what he defines as the center of gravity, analyzing the density gradients for a variety of cities worldwide. Then, he uses this measure to compare various degrees of monocentricity along its consequences on urban poverty and pollution.
Bertaud’s
methodology falls short in identifying the location of multiple centers in a
polycentric structure. A more dynamic approach to localize places of attraction
would be to look at flows of people. This is what Zhong, Müller, Huang and
Schmitt (reading #2) do, by looking at three transportation surveys in
Singapore. The authors built a measure of centrality based on the density of
trips and the diversity of activities performed at each travel destination.
This measure is able to capture the polycentric structure of Singapore,
identifying four other regional centers of activity additional to the CBD, as
they change over time.
Measures of
centrality based on either population density or trips are good in recognizing
the spatial structure of the city, while identifying clusters of production and
consumption. However, they fail to exhibit the spatial structure of local labor
markets. In other words, they do not differentiate between centers of production
by type of industry, and centers of consumption by type of occupation-income.
Lambert and Birkin (reading #3) propose a microsimulation analysis to build a
synthetic population to identify local concentrations of employment to
characterize the local labor market, which enables an exploration of the
spatial dimension of social segmentation in the city. However, this approach
lacks a dynamic structure to know where workers travel besides their place of
work.
Putting the three readings together: an exploration of urban form, plus travel data at the individual level, plus a synthetic population localizing place of work, residence, and type of occupation, it might altogether let us to identify different clusters of production by industry type and clusters of consumption by type of occupation. This information would enable the study of the social stratification of urban space by places of work, residence and consumption. For instance, a center of production for certain type of workers could be a center of consumption to other types. In contrast, some other centers clusters of consumption and production might mix people from different income groups. This information and methods put together would facilitate the study of the spatial dimension of social segmentation of the urban space.
1. Bertaud, Alain. "The spatial organization
of cities." Deliberate
Outcome or Unforeseen Consequence, Background Paper to World Development Report
(2003).
2.
Zhong, Chen,
Stefan Müller Arisona, Xianfeng Huang, and Gerhard Schmitt. "Identifying
spatial structure of urban functional centers using travel survey data: a case
study of Singapore." In Proceedings
of The First ACM SIGSPATIAL International Workshop on Computational Models of
Place, pp. 28-33 (2013).
3.
Lambert, Paul,
and Mark Birkin. "Occupation, education and social inequalities: a case
study linking survey data sources to an urban microsimulation analysis."
In Employment Location in
Cities and Regions, pp. 203-222. Springer Berlin Heidelberg (2013).
Supplemental Readings:
Discussion Questions:
1.
Bertaud
considers three aspects of urban spatial structures: the pattern of daily
trips, the average built-up density, and density gradient. What other
variables/data do you think might also reveal the urban spatial structure?
2.
How
new technology (e.g. sensors) could improve the measurement of spatial
structures?
3.
How
new technology (e.g. autonomous vehicles) could modify the urban spatial
structure?
4.
How
different the spatial structure of Singapore would be if its structure had been
influenced exclusively by the market, without intervention from planning
agencies? Still monocentric? Polycentric but with a different spatial location
of the centers?
5.
What
local labor markets can tell us about the social segmentation of urban space?
6.
In
which other ways social segmentation and segregation get visible throughout the
urban space or urban form?