Planning Sustainable Cities: Coordinating Accessibility Improvements with Housing Policies

Emerging mobility services (such as mobility-on-demand and micromobility) have expanded the range of travel options available to individuals and offered ways to improve access to various opportunities. Unlike mass transit services, emerging mobilities can be implemented and experimented with rather rapidly. As a result, they are also likely to induce relatively rapid changes in travel behavior and location choices. Several cities across the world are experimenting with car-lite policies that aim to reduce auto ownership and use (and emissions) with the help of emerging mobilities, transit improvements, and/or urban design. Therefore, it becomes important to understand the near-term effects of emerging mobilities on neighborhoods through the lenses of vehicle ownership and residential location choice over the first few years of change.

In my dissertation, I used an agent-based land use-transportation interaction (LUTI) microsimulation model to explore ‘what-if’ scenarios in Singapore regarding how households might react to policies that restrict private vehicle ownership and improve non-auto accessibility. I found that private vehicle restrictions alone without complementary non-auto accessibility improvements can reduce accessibility and social welfare, even in a transit-rich place like Singapore. Solely imposing a blanket ban on private automobiles to accelerate the transition to a sustainable mobility future will likely do more harm than good. Evidence of accessibility-induced gentrification, to varying degrees, was found in all of the Singaporean neighborhoods I explored. Lowerincome and less auto-dependent neighborhoods seem to be more prone to accessibility-induced gentrification, thereby suggesting that non-accessibility improvements alone may not guarantee equitable outcomes. I then explored two housing policies – upzoning and parking restrictions – as possible strategies to mitigate the gentrification side-effects. Both policies appeared to have limited value by themselves because, at times, they could accelerate gentrification or reduce social welfare. However, they became much more effective policy instruments when combined with affordability constraints (such as income restrictions and price discounts), so that the accessibility and welfare benefits of car-lite policies could be equitably distributed across residents.

Alex Boccon-Gibod

Thesis Advisors: Mary Anne Ocampo, Jim Aloisi