Eva Heinena and Giulio Mattio published an article titled “Multimodality and CO2 emissions: A relationship moderated by distance” in the latest volume of Transportation Research Part D. The article tests the relationship between multi-modality and carbon emissions, finding that distance contributes much more to emissions than relative levels of multi-modality.
The perhaps surprising finding of the study: many multi-modal trips aren’t effective in reducing emissions. Here’s how the authors describe that finding in the abstract: “We find that the level of multimodality is only weakly associated with CO2 emissions. It is only when controlling for levels of travel activity (trip frequency, total distance travelled) that a moderate association in the expected direction is observed (i.e. that higher levels of multimodality correspond with lower CO2 emissions).”
The authors note that the reduction of carbon emissions is not the only goal of public transit, but that the research makes it clear that merely supplying multi-modal options will not be enough climate mitigation activity. “More attention needs to be paid to the key role of high levels of travel activity, and how these could be reduced,” according to the study’s authors.