A study of the slipstreams of high-speed passenger trains and freight trains

As the speeds of both passenger and freight trains increase, there is increasing concern that the unsteady gusts generated in train boundary layers and wakes will become more of for a risk to passengers waiting on platforms and for trackside workers. In addition, the demands of interoperability make this a problem of growing relevance to railway operators across Europe. A number of model scale and full-scale experiments have been carried out in recent years that have provided robust experimental data to quantify these flows. This paper considers all the available datasets for high-speed passenger trains and container freight trains, and in making a comparison between them, arrives at a number of conclusions concerning the characteristics of train slipstreams. It is concluded that the identification of a number of distinct flow regions in earlier work is generally valid and forms a useful framework for the consideration of the problem. The flow characteristics are different in each region, and, depending upon the train type, the measurement distance from the train and height above ground, the observed peak gusts for a train may occur at any time during the train passage or in its wake. It is also concluded that results obtained from measurements around small scale moving models are in good agreement with the full scale measurements and reproduce all the important flow features.