Assessment of the impact of a public transportation infrastructure on the change over time in greenhouse gas emissions of a city: case study of the Vancouver SkyTrain's Canada Line

The transportation industry is a vector of important change to meet the challenges of sustainability and resilience of our societies. It is the second largest GHG emitter in Canada, accounting for nearly 28% of the country's total emissions. Among these emissions, 57% were attributable to the travel of Canadians in 2021, of which 30% are linked solely to the use of private cars. To limit their circulation, the development of public transit infrastructure is an effective way. However, such infrastructure has indirect effects on GHG emissions due to its interdependence with the urban planning and its socio-economic characteristics. This research paper aims to evaluate the impact of the commissioning of a public transit infrastructure on the evolution of a city's GHG emissions over time. The case of the Vancouver SkyTrain's Canada Line was analyzed. The methodology used to carry out this study is a synthetic control. This is one of the contributions of this research to the existing literature, whose studies generally only assess the direct effects of a transportation infrastructure from the emissions avoided by the modal shift of passengers. The data analyzed was collected from the open databases of Canadian cities and Statistics Canada. These include GHG emissions in CO2 equivalent, GDP, gasoline and fuel tax revenues, construction investments, number of inhabitants and their transportation habits in the cities in the control group. The results show that the introduction of the Canada Line resulted in an increase of approximately 8.6% in Vancouver's GHG emissions in 2011. This increase could be explained by the redevelopment of neighborhoods around infrastructure stations to the detriment of their gentrification, accentuating urban sprawl. For an investment in a sustainable means of transport to effectively reduce GHG emissions in the long term, more emphasis should be placed on the interactions between transport, urban development (to be built or renovated) and the socio-economic characteristics of neighborhoods. Studies with more spatial precision would provide a better understanding of the interweaving of social, economic, and environmental changes generated by transportation infrastructure and affecting a city's GHG emissions.