Tracks for Tilting Trains-A Study within the EU Project Fast and Comfortable Trains (FACT)

摘要

The tilt mechanism reduces the lateral acceleration perceived by the passengers. Therefore, tilting trains, if provided with a suitable running gear, may run at higher cant deficiencies than non-tilting trains. However, the nominal track geometry still defines a ceiling for permissible train speed, but at a higher level.rnThe research project Fast And Comfortable Trains (FACT), organised by the European Commission and the UIC, had the overall objective to identify procedures to enhance the performance of tilting trains, without compromising passenger comfort and safety of the system.rnFACT Work Package 1 had the objectives to provide methodology for upgrading infrastructure to achieve the optimal performance for using tilting trains, with special attention to mixed traffic conditions and to identify economical design of track and/or coach for a given performance and a given comfort level.rnIn the research report produced within FACT WP1, Tracks for tilting trains, a general overview of considerations for the track is given, and a state-of-the-art overview of research on track/vehicle interaction, with a focus on the track geometry, is presented.rnThe major track aspects of tilting trains are related to the horizontal alignment and cant, since the relation between low-frequency variables, such as low-frequency roll velocity, low-frequency lateral jerk etc. depends to a high degree on the horizontal alignment. Alignment design is a balancing act between conflicting objectives, such as large curve radii and long transition curves. Furthermore, the Tracks for tilting trains report covers the shape of the transition curves (linear versus S-shaped curvature functions), the lengths of track elements between transition curves, vehicle dynamics at curve entries without transition curves.rnImportant conclusions, among others, are:rn• The optimum transition curves are longer for tilting trains than for non-tilting trains.rn• Lengths of circular curves between transition curves are not important for wheel/rail forces and passenger comfort.rn• Horizontal curves without transition curves eliminate the advantage of tilting trains.rn• Tilting trains may run at high cant deficiencies also at speeds above 250 km/h.rn• Under certain conditions, tilting trains are very suitable for mixed traffic with slow freight trains.rnThe FACT WP1 also analysed proposed limits for various track variables in a draft European standard for alignment parameters (CEN - prEN 13803-1, dated 2004) and recommended that this proposal should be changed in order to avoid situations with unacceptable values for the rate of change of cant deficiency.rnThe FACT WP1 report Tracks for tilting trains is the first report of its kind, focused on the track aspects of tilting trains. The research report presents a comprehensive overview of studies of track/vehicle interaction relevant for alignment considerations for tilting trains, summarises track geometry standards from various countries using tilting trains, and compares the standards with respect to passenger comfort.