Global Street-Network Urban Sprawl and Climate Policy

Principal Investigator: Chris Barrington-Leigh
Co-Investigator: Adam Millard-Ball (UC Santa Cruz)
Funding: SSHRC Insight Grant

The planet's population is undergoing the last phase of becoming urbanized, a once-only process resulting from technological advance and the centralization of resources. The scale of this process is unprecedented. Between 2010 and 2025, China is expected to design and build the equivalent of an entire United States of new city roads, homes, and infrastructure. Meanwhile, over the last century, urban development has increasingly taken the form of sprawl, characterized by low densities, spatially segregated land uses, and a street network with low connectivity. Yet poor urban planning has consequences for economic productivity and efficiency, health, equity, lifestyle and well-being, and the environment. Moreover, once laid down, the pattern of streets determines urban form and the level of sprawl for many decades to come. Buildings may come and go, but the street layout is generally permanent, even in the face of large market and institutional shifts. The pace of the remaining urbanization is so high as to make the decisions about how urban streets are laid down one of the largest, most permanent investments humans are making, with far-reaching implications for future transportation, consumption, quality of life, and climate.

Using recently developed methods to analyze the connectivity of urban streets, this research will:

1. Develop a global map of street network connectivity covering most countries, comprising street-by street measures of network structure. Conduct a comparative analysis of urban form across countries and cities.
2. Characterize the dynamic evolution of road networks by adding a time dimension to our data, using newly available global time series overlays of urban extents. This will facilitate a global comparison of the patterns and trends in urban form investments in countries and individual urban areas. In addition, for select countries including Canada, we will use more extensive national statistics to generate multi-decade, high-resolution time series of the network properties of new street investments.
3. Contribute to the subjective well-being literature by investigating the relationship between urban form, community and social capital, and high-resolution life satisfaction data.
4. Analyze long-term market outcomes for areas characterized by road network sprawl. For select countries, including Canada and the USA, we will characterize long-term residential densification trends and long term land value appreciation as a function of the original road network characteristics.
5. Articulate a microeconomic theory of road network sprawl spillovers, capturing the path-dependent effects of fuel price and pre-existing nearby urban form in influencing the choice of new urban form. Using this model and our time series data, evaluate the relative benefits of two classes of policy: (1) carbon pricing and (2) planning restrictions explicitly targeting the road network.

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