Recent experiments allow to define aerodinamic effects of high speed trains in tunnels. On this ground it is possible to define the aims of another series of experiments in order to determine the functional relationship between some variables, which are to be fixed during the project, and some relevant physical quantities. At the present time it is possible only to create some suppositions about these functions but it appears evident the necessity of a quantitative analysis to be done as soon as possible in order to plan tunnels correctly.
