Full scale experimental tests to evaluate the train slipstream in tunnels

The train slipstream, i.e. the air velocity induced by the train, is one of the most important aerodynamic effects connected to railway vehicles because it has a direct impact on the safety of passengers on the platform and track workers along the railway line. In recent years, a lot of studies were performed to understand the development of this phenomenon in open field, and specific EU standards, the EN 14067–4 and the TSI were issued. Instead, only few studies have been carried out to analyse the train slipstream in confined spaces (as tunnels, line sections with acoustic barriers, etc.), even though the first results of these analyses have shown that the confinement of the air causes more severe conditions regarding the speed of the air flow. This work aims at studying, through a fullscale experimental campaign, the effects on the air flow speed caused by the train passage. The effects of different train parameters (i.e. train type and length, etc.) and infrastructure parameters (i.e. geometry variations) were analysed. Lastly, the results of a specific test considering the presence of a stationary train inside the tunnel while another train is passing are described, to simulate scenarios of ordinary railway traffic.