The aim of the MMUST is to develop a decision support tool and to evaluate transport policies in favour of cross-border mobility in the Greater Region. This tool is being developed through a scientific partnership involving researchers working on mobility and transport from three of the countries in the Greater Region and through consultation with the main public actors that manage the mobility flows studied. The tool developed has the following features: a unified approach to all the mobility transport data available, a multimodal approach allowing the impact to be assessed of all types of transport existing or to be promoted and prospective approach through the evaluation by enquiry and modelling of different alternative mobility scenarios.