Assessing the Effects of New Light Rail Transit on Regional Traffic Congestion and Transit Ridership: A Synthetic Control Approach

Traffic congestion has been a significant issue across the large cities. Though a considerable body of research has investigated transit ridership and traffic congestion effect of new transit service, most research focuses on the effect at a corridor level or for localized areas, little research has examined the long-term effect of large transit projects on transit ridership and traffic congestion at the regional level, and the causal relationship between transit and its effect on traffic congestion and transit ridership is rarely analyzed in the literature. This study attempts to address this gap by conducting an empirical analysis in three Urban Areas (UAs). Using the synthetic control method, this study quantified the causal impacts of newlRT lines on ridership and traffic congestion. Results indicate that LRT contributed to traffic congestion relief and transit ridership increase, and that the effect changed over time and varied across UAs. This study provides empirical evidence for the effect of new LRT on traffic congestion and transit ridership and contributes to the ongoing debates concerning the effectiveness of LRT service to increase transit ridership and relieve traffic congestion.