Which incentives toward sustainable mobility solutions for medium and short distances in Ile-de-France?

Reducing the negative externalities of road transport requires a reduction in private car use and a modal shift to other sustainable modes. However, little research has been conducted on combining economic and non-economic incentives to change commuter behavior, from solo driving to carpooling, public transit, and electric bicycles for medium and short distances (to work or school). Based on a questionnaire conducted on 1502 respondents in Ile-de-France, we model the impact of economic incentives for sustainable and non-economic mobility and the combination of both incentives on modal shifts for medium and short distances through nested Logit models. We examine separately (1) the impact of non-economic incentives such as nudging on medium-distance commuting trips. We also study the effect on the health of various transportation modes and the social norm for short-distance travel. Similarly, we examine (2) the impact of an economic incentive alone and (3) the combination of economic and non-economic incentives separately. The economic incentives refer to the employer's subsidy for sustainable mobility (called "Forfait mobilité durable" or "FMD" in French) and the 250-euro carbon tax. The results show that the combination of the 250 Euro carbon tax and nudge is very effective in shifting the modal shift to carpooling and public transport among young adults, low-income households, and people with a high level of education for medium distances. For short distances, nudge is effective for the choice of carpooling and electric bicycles among young adults and for the choice of public transport among people with a high level of education.