The values of dedicated right of way to transit ridership and carbon emissions

Project summary:

Transit agencies have adopted various types of right of way (ROW) for transit routes--including mixed traffic, semi-exclusive ROW, exclusive ROW, and grade separation--but few empirical studies have quantified their impacts on ridership and carbon emissions. Using data collected from transit agencies in the US, this research aimed to examine the impacts of dedicated ROW. Researchers applied the gradient boosting decision tree method to estimate the nonlinear relationships between yearly route-level transit ridership and five types of independent variables, with a focus on ROW. The results showed that ROW contributes 18 percent of the power to predicting transit ridership, which is the largest among all the independent variables. Upgrading from mixed traffic to semi-exclusive ROW could boost ridership by 70,000 on average. A further upgrade to an exclusive ROW could add 3.68 million passengers.

Moreover, the number of stops, transit route commence year, population density, signal priority, number of park-and-ride facilities, headway, network density, and route length all have non-trivial contributions to predicting ridership. Upgrading the operating environment could substantially reduce carbon emissions, up to 6.37 million pounds of CO2 equivalent. Overall, elevating ROW levels could notably enhance transit ridership and reduce carbon emissions, locating transit routes in the areas with adequate population density and network density could improve their performance, deploying signal priority and improving transit frequency also help, and increasing the share of electric buses could further decrease carbon emissions.