Sustainable transportation analyses consistently use average-rate methods (per unit of passenger travel) to quantify the emission impacts of travel behaviour and transport policy, although this approach fails to represent the marginal impacts (i.e., the change in total emissions due to an action or policy). This distinction can be described as attributional (average-rate) versus consequential (marginal-rate) accounting frameworks. As shown in the papers below, average-rate methods systematically under-represent the environmental and climate benefits of shifting travel away from private motor vehicles, in addition to other distortions. This line of research challenges and aims to change the standard of practice in sustainable transportation analysis by developing methods for and demonstrating the benefits of marginal accounting in emissions analysis.
Bigazzi, A., “Comparison of marginal and average emission factors for passenger transportation modes.” Applied Energy, Vol. 242, pp. 1460-1466, 2019.
Bigazzi, A., “Marginal emission factors for public transit: Effects of urban scale and density.” Transportation Research Part D: Transport and Environment, Vol. 88, 2020.