Impacts of transit-oriented development on car use over a 10-year period in Porto, Portugal: From macro- to micro-analysis

Transit-oriented development (TOD), an urban planning concept that aims to promote sustainable transport modes, has been actively studied in recent years, especially in relation to car trips reduction. However, longitudinal studies on the matter are still rare. In this paper, we analyze the effects of the implementation of a new metro system after its first 10 years of operation focusing on how changes in the number of car trips were influenced by station type–TOD, transit-adjacent development (TAD) and park-and-ride (P&R). Specifically, we perform a before/after analysis of the impact of metro implementation in the Porto area (Portugal) both at a macro scale (civil parish) and at a micro scale (census tract) to analyze the overall effect of metro and more detailed effects only detectable at the micro scale. Census-tract data enables a comprehensive analysis of spatial spillover impacts from different stations, comparing the extent (i.e., the distance range within which the effect of station proximity is noticeable) and the magnitude (the reduction in the number of car trips) of the spillover in each case. Both direct and indirect metro impacts are already visible at the macro scale, yet at the micro scale the magnitude of the spillover effects varies depending on station type. The effects of TOD stations on the reduction of car trips are the strongest across the different station types and are felt up to a 2 km distance from a station, while TAD and P&R effects are weaker and do not reach beyond 1.2 km.