Part of a series of “reading memos” that offer a brief summary of interesting academic content along with my personal reflections. This one covers Chapter 9 (Land Use Impacts of Transportation Investments) of Giuliano & Hanson’s The Geography of Urban Transportation.
Transportation and land use have interdependent dynamics: transportation investments influence accessibility (the ease of moving between places), which affects the location of activities (land use patterns), which modify daily activity/travel patterns, which in turn affect the transportation system. Regional growth is defined as the addition of more activities located in places that have become more accessible.
A couple of land use theories offer to predict the relationship between transportation costs and land use. The standard urban economic theory posits that people choose their residential locations based on utility-maximization of land rent, commuting costs, and costs of all other goods/services – this suggests that a reduction in commuting/transportation costs (by reducing monetary costs or increasing travel speed) would result in movement away from city centers (decentralization) and an increase in consumption of housing, with a greater effect on higher-income groups.
Employment location theory likewise models employer locations as a function of land rents, commuter costs, etc. – but notes that employment locations will always be more concentrated than residences due their consideration of total transport costs including production inputs and goods to market. Both theories are limited with assumptions of monocentric cities, a perfect housing/transport tradeoff, identical household preferences, perfectly competitive land markets, and static/instantaneous equilibrium across all markets.
When applied to highways, the theories suggest the greatest benefits are generated at the site of new highway investments but that the impacts are context-specific (most significant where there is growing population & employment with readily available land) and there is little evidence that this kind of investment is effective for promoting net economic development (i.e., it is more likely redistributing activities from other locations).
When applied to public transit, the theories note that rail investments typically replace bus lines (which limits their influence on accessibility), resulting in highly localized impacts that are most likely to occur in fast-growing and heavily congested core areas with strong demand for commercial/residential development.
The employment location theory suggests that employers that produce goods with no transportation costs (such as information/technology) should eventually become distributed, following their employees / general population. Yet it seems that that this trend was progressing quite slowly up until 2020 – the value of agglomeration kept tech hubs such as San Francisco highly relevant and rapidly growing, but it remains to be seen what the long-term impacts of pandemic-induced adoption of remote work will be.
Given the complex relationship between land use and transportation, it was understandable that the current theories were not sufficient to conclude whether specific types of investments (like rail) would always have reliably predictable impacts on land use patterns. Instead, the findings that showed outcomes depended more on the underlying conditions of the city (population characteristics, economic potential, local jurisdictional policies/zoning, etc.) made sense and reflected the mixed results seen across the world of transportation infrastructure projects. The takeaway from the example of high-speed rail (that overall increase in intercity accessibility would not be significant without well-developed feeder transit systems) was especially poignant given the current discussions about the future of California HSR.