Méthodologie pour l'analyse d'une répartition modale et spatiale plus durable du trafic

There has been a significant growth in freight traffic over the last few decades in Europe. The Alps, located in the middle of North-South route, are particularly sensitive regarding this evolution because of their topographic and climatic characteristics. The more flexible road transport has the advantage of meeting the requirements of contemporary production and distribution techniques, thus helping to explain increasing modal split for road transport. The development of road transport resulted in increased air and noise pollution, congestion, and safety concerns (accidents). The advent of the concept of sustainable development has called current modal split into question. It mainly covers the temporal dimension (equity between generations), but sustainable development also has to take into account the territorial dimension (equity inside the same generation). In this context, the consideration of the interaction between traffic and territory is essential. To assess the vulnerability of crossed areas to traffic and mainly to road and railway transalpine freight traffic, in particular to the nuisances they induce, a method has been developed. The use of a Geographic Information System and the development of an indicator system show the interest of this approach to evaluating the impact induced by a modal and/or spatial split of a volume of transalpine freight traffic (scenarios) on the crossed regions' sustainability. Developed to help decision-makers to take decisions meeting the sustainable development objectives, this method counts for the whole "Alpine segment" (Fréjus – Brenner) and is tested on the Swiss territory. The application on the Swiss territory takes railway and road traffic into account and the noise and air pollutions they induce. The development of indicators is based on immission data (concentrations) and on the spatial distribution of the population. This PhD thesis shows that the establishment of relationships between data coming from various sources is possible, even indispensable, to analyse the effect induced by a modal and/or spatial change of transalpine freight traffic. The results of this research reveal that transalpine freight traffic has a significant impact on the short term. To reduce this impact, it appears to be necessary to act on transalpine freight traffic but also on freight traffic in general. A change in a modal and spatial split of a transalpine freight traffic volume is able to reduce this impact but the situation will still not be satisfying.