Multi-scale urban passenger transportation CO2 emission calculation platform for smart mobility management

•Propose a bottom-up CO2 emissions calculation approach based on sparse individual trip chain data;•Propose a novel multimodal individual trip chain identification and reconstruction method;•Propose two city-scale trip information expansion methods based on population and checkpoint data;•Develop a multi-scale high-resolution transportation carbon emission calculation platform;•Explore potential implementations of carbon reduction policies in the transportation sector.