Environmental impacts of ridesplitting considering modal substitution and associations with built environment

Ridesplitting promises to reduce emissions. Previous studies mainly compared ridesplitting with single rides like taxis, leaving its impact on other modes unclear. This study quantifies the reduction or increase in CO2 emissions due to ridesplitting from a modal substitution perspective and explore the nonlinear impacts of built environment factors on emission reductions. Considering different urban contexts, we choose Chengdu and Xi’an as representative examples for analysis. The results indicate that most ridesplitting trips lead to an increase in CO2 emissions when compared to other modes. In Chengdu, a mere 8.92% of ridesplitting trips result in emission reduction, whereas in Xi’an, this figure stands at 4.68%. Emission reduction is predominantly linked to taxi substitution. Moreover, many built environment factors exhibit positive relationship with the increase in emission resulting from ridesplitting, and present nonlinear and threshold effects. The findings offer a framework to assess ridesplitting’s environmental benefits, aiding urban planners and policymakers.