Monitoring Global Expansion

The secondary mission of the NYU Urban Expansion Program is to gain a better understanding of urban expansion the world over by monitoring it in the entire universe of the 4,000+ cities, and by collecting and analyzing evidence on the quantity of land required for urban expansion, on its physical organization and its affordability, and on the forces affecting it in a stratified global sample of 200 of these cities.
There is great reluctance to engage with the prospects of urban expansion, for reasons that may be perfectly understandable. Many people believe the cities consume enough land as it is, and all future construction should take place within their current boundaries. Many oppose expansion so the planet can remain sustainable, people can walk and cycle at their leisure, municipal budgets are not unduly burdened, decaying central cities can thrive again, and precious cultivated lands on the urban fringe are not laid to waste. This reluctance tends to keep such prospects rather obscure and even somewhat frightening, and prevents us from addressing them in a clear and forthright manner.

The NYU Urban Expansion Program has embarked on a multi-phase research effort to monitor global urban expansion. The research effort focuses on the universe of all cities and metropolitan areas that had 100,000 people or more in 2010, and on a stratified global sample of 200 cities chosen from that universe (see figure 1). We have conducted a statistical test to determine whether the sample is truly representative of the universe of cities by checking whether the mean population growth rate in the sample is the same as that of the universe as a whole. We can say with 95% confidence that the two are not different from each other.The more ambitious goal of the monitoring program is to have more and more data collected for this sample on a regular basis.

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Figure 1: Map of the world showing the division into the eight world regions and the global sample of 200 cities.

The sections below describe progress to-date on the various phases of monitoring global urban expansion.

Phase I: The Atlas of Urban Expansion-the 2015 Edition

The Atlas of Urban Expansion: The 2015 Edition is a joint project of the United Nations Human Settlements Programme (UN Habitat), the Lincoln Institute of Land Policy, and the NYU Stern Urbanization Project. The Atlas will be modeled on the earlier Atlas of Urban Expansion published by the Lincoln Institute of Land Policy in 2012 (online at: http://www.lincolninst.edu/subcenters/atlas-urban-expansion/). That Atlas provided satellite-based maps of urban extent and their associated metrics—including extent, built-up area density, fragmentation, and compactness—for a global sample of 120 cities for 1990 and 2000. This sample was a 3.3% stratified sample of the universe of 3,646 cities that had 100,000 people or more in 2000. The new Atlas of Urban Expansion: The 2015 Edition will use the same methods to provide the same maps and metrics for a global sample of 200 cities for 1990, 2000, and 2010. It will have maps and metrics for all 200 cities for three dates, 1990, 2000 and 2013, following the same format as the earlier Atlas of Urban Expansion.

Phase II (a): The quality of urban layouts in expansion areas

This phase of monitoring global urban expansion is a joint project of United Nations Human Settlements Programme (UN Habitat) and the NYU Stern Urbanization Project. It focuses on the quality of urban layouts in the expansion areas in the global sample of 200 cities. Using the high-resolution satellite imagery of Bing and Google Earth, we focus on a random set of 10-hectare locales in the expansion areas of cities (areas developed between 1990 and 2013). In each city, we seek to obtain average measures for five metrics: (1) the share of land in arterial roads and access to arterial roads; (2) the share of land in streets and the distribution of street widths; (3) the share of land in residential areas in different stages of housing sector evolution (atomistic housing, informal land subdivisions, formal land subdivisions, and housing projects); (4) average block size and the density of street intersections; and (5) plot dimensions in land subdivisions. The bulk of this work, which is quite labor intensive, will be done in the India Urban Expansion Observatory in Navi Mumbai, India. Its work should be completed by the end of 2015. The analysis and the subsequent report on the results should be available in time for Habitat III, the Global Conference on Human Settlements now scheduled for the summer of 2016.

Phase II (b): The quality of urban layouts in a sub-sample of entire cities

This phase of monitoring global urban expansion is also a joint project of United Nations Human Settlements Programme (UN Habitat) and the NYU Stern Urbanization Project. In an extension to the Phase II work in expansion areas, we plan to measure the same metrics in the entire areas of 30 cities, a global sub-sample of the larger sample of 200 cities. For these 30 cities, we have maps showing the time that different parts of these cities were built up, going all the way back to 1800. In these 30 cities, we plan to divide the area built before 1990 into 4 sub-areas: (1) areas built before 1900; (2) areas built between 1900 and 1930; (3) areas built between 1930 and 1960; and (4) areas built between 1960 and 1990. Again, using a random set of 10-hectare locales in each of these areas, we plan to measure the same five metrics listed in the section above. This study will allow us to study the changes in these metrics over time in rigorous and systematic manner.
The data collection part of this study will be undertaken by Grupo gvSIG in Valencia, Spain. The NYU Urban Expansion Program, in collaboration with gvSIG will analyze the data and prepare a report based on the results. The methodology for data collection is now being tested in two pilot cities, Tokyo and Paris. There is agreement in principle on the partnership between UN Habitat and the NYU Stern Urbanization Project to carry out this study, as well as on a budget for undertaking the study. The work on this study is due to start in early January 2015 and be finished by the end of 2015 in time for a report to be prepared for Habitat III.

Phase III (a): A telephone survey of the regulatory regime governing land and housing in expansion areas

This phase of monitoring global urban expansion is also a joint project of United Nations Human Settlements Programme (UN Habitat) and the NYU Stern Urbanization Project. The aim of this survey is to obtain information on the rules and regulations that govern zoning, land use, land subdivision, and building construction in areas of expansion in the global sample of 200 cities. The focus here will be on rules that are actually enforced, rather than on rules that are on the books. The survey instrument is now in preparation, awaiting additional inputs from expert advisors as well as from UN Habitat. We plan to test the survey instrument in six cities: Shenzhen, China; Pune, India; Addis Ababa, Ethiopia; Zwolle, the Netherlands; Springfield, MA, USA; and Valledupar, Colombia.

Phase III(b): A real estate broker survey of the affordability of land and housing in expansion areas

This phase of monitoring global urban expansion is also a joint project of United Nations Human Settlements Programme (UN Habitat) and the NYU Stern Urbanization Project. We are currently also pursuing the possibility of forming a partnership with the McKinsey Global Institute as well. The aim of this survey is to find out whether land and housing in the expansion areas of cities are affordable to the majority of urban households. If they are not affordable, the earlier phases of the monitoring initiative may help us explain why. This study will focus on the price and characteristics of plots of land in formal and informal subdivisions, as well as land-and-house packages and apartments in the expansion areas of cities. We will seek to obtain this information for the entire area of expansion that, in large metropolitan areas, may consist of more than one land and housing market. To this effect, we will need to employ real estate brokers and ask them to assemble this information (including location information) for a large number of units in each city, focusing on units which my be affordable by median-income families and typically excluding luxury units. In parallel, we shall seek to obtain reliable information on household income quintiles in the cities studied.