: This paper investigates the impacts of several implementations of daily mobility policies and external shocks on social costs, with a particular focus on carpooling. This social cost is calculated considering consumer's cost, external costs, as well as the expenses and incomes of public authorities and private companies. Four transport modes are considered: solo driver, carpool driver, carpool passenger and public transport. A modal choice model is then applied to trips with 6,287 different origin-destination of the eastern Lyon area. Simulations of time-gain and monetary scenarios are then realized to observe impacts on demand and consequently on the other parameters affecting the social costs. Our results show that consumer's costs explain the majority of the total social cost. Values commonly used for externalities barely impact the social cost in the simulations and traffic reduction measures impact more public and private revenues than they reduce externalities, leading to higher total social costs. Mor[...]
: This paper reviews the contribution of experts to the appraisal of large infrastructures, looking at the evaluation performed in 2019 in Italy by the Ministry of Infrastructures and Transports on the Lyon-Turin railway project. This evaluation had been initiated in a particular context, linked to a visible policy agenda and while the construction of the tunnel had already begun. The appraisal has produced surprising results, mostly counterintuitive and heavily criticized. We analyse these results and show how they can be valid, in that they would not result from inconsistency in the method but from the peculiar features of the project (low initial demand, high mode transfer compared with initial traffic, high road tax and toll levels). We also check the validity of some paradoxical results of the assessment. Moreover, the public debate has been made more difficult due to an inconsistency in EU evaluation Guidelines. Also, we analyse mechanisms that affect the credibility of experts and we find that the influ[...]