The transportation sector and low-carbon growth pathways: modeling urban, infrastructure and spatial determinants of mobility

Abstract : There is still a controversy as to the effect of spatial organization on CO2 emissions. This paper contributes to this debate by investigating the potentials offered by infrastructure measures favoring lower mobility in the transition to a low-carbon economy. This is done by embarking a detailed description of passenger and freight transportation in an energy-economy-environment (E3) model. In addition to the standard representation of transport technologies, this framework considers explicitly the "behavioural" determinants of mobility that drive the demand for transport but are often disregarded in mitigation assessments: constrained mobility needs (essentially commuting) imposed by the spatial organization of residence and production, modal choices triggered by installed infrastructure and the freight transport intensity of production processes. This study demonstrates that the implementation of measures fostering a modal shift towards low-carbon modes and a decoupling of mobility needs from economic activity significantly modifies the sectoral distribution of mitigation efforts and reduces the carbon tax levels necessary to reach a given climate target relatively to a "carbon price only" policy. This result is robust to a wide range of assumptions about exogenous parameters.