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.

Few studies have analyzed the mobility impacts of TOD using a longitudinal research approach, and even fewer incorporated origin–destination (OD) information in the analysis. In this paper, we examine the impacts of a metro system with TOD features on the share of car and bus trips using Metro do Porto as a case study. The application of an autoregressive beta regression modeling approach to parish and OD data from two mobility surveys (2000 and 2017) allowed to detect changes in travel behavior accounting for pre-metro mode shares. Metro implementation was associated with strong reductions of the share of car trips in OD pairs with metro at both trip ends, especially when stations were TOD. Metro influence on the share of bus trips varied from neutral to positive, suggesting that bus and metro complement each other rather than compete for passengers.

Among the attempts made worldwide to foster urban and transport sustainability, transit-oriented development (TOD) certainly is one of the most successful. Since the TOD concept appeared in the late 1980s, it has received increasing attention from researchers and practitioners as a way to merge together transport engineering and planning, land-use planning, and urban design for providing comprehensive solutions to contemporary urban problems. This attention has notably led to the publication of over 300 articles explicitly concerned with TOD in Web of Science journals, as well as to many implementations of the concept, some already completed and others underway (as, for example, the Grand Paris Project in France and Moscow Central Circle in Russia). Essentially, TOD can be described as land-use and transport planning that makes sustainable transport modes convenient and desirable, and that maximizes the efficiency of transport services by concentrating urban development around transit stations. However, as TOD projects started to be implemented worldwide, it became evident that their outcomes could be quite diverse, revealing that in practice the results of a project would depend on a wide variety of factors, trends and complex interrelations between them. In this article, we aim to provide a comprehensive, systematic and up-to-date review of TOD research achievements and challenges. We start by presenting the TOD concept, framing it in the theory of urban planning, and by describing the different typologies of TOD proposed in the literature. Then, we review the vast research dedicated to the study of TOD effects, distinguishing impacts on travel behavior, real-estate prices, residential location, urban form, and community life. The next subject we look at is TOD planning, focusing separately on policy issues and decision-support tools. In the final part of the article, based on the analysis of previous literature, we identify the main gaps and challenges that TOD research needs to address in the future.