DYNAMIC SIMULATION OF THE ALVIA TALGO SERIES 730 TRAIN

24 July 2015 was the second anniversary of the derailment of a Talgo series 730 train on the approach to the Santiago de Compostela station. The train, made up of two locomotives and eight cars, was covering an Alvia service at the time of the fatal accident.

Many hypotheses have been advanced and studies performed with the aim of determining the exact circumstances of the crash, not only to deepen our understanding of the facts but also to ensure that the same set of circumstances is never repeated.

CITEF, on request of the expert witness appointed by the investigating judge of the judicial inquiry into the accident, has developed a dynamic simulation of the train’s movements that provides accurate knowledge of the behaviour of the Alvia Talgo 730 in the moments prior to the derailment. The conclusions drawn from this simulation now form part of the inquiry documentation.

The assessment of the behaviour of the vehicle on the curve where the derailment occurred entails a three-way analysis consisting of: a static analytical study to obtain an estimate of the approximate overturning speed; a quasi-static study that simulates the behaviour of the vehicle at different speeds, the purpose of which is to define the speed at which the vehicle would derail on transiting the curve; and thirdly a dynamic study that recreates the actual conditions under which the accident occurred.

At the same time the dynamic response of the vehicle on transiting the curve in question at the maximum permitted speed was studied to establish a comparative reference between the two situations.

A model of the Alvia train and of the track section on which it was derailed were developed especially for the purposes of the simulation. The dynamic simulation was run in the time domain once the vehicle-track interaction models had been completed. This study not only takes analysis of the Talgo series 730 into account but also the series 130 that serves as a point of comparison with the derailed train since the 730 is a later version of the 130.

Here at CITEF we hope and trust that circumstances such as those that led to this accident will not be repeated in the future, and with that objective we are committed to working to enhance the safety and efficiency of rail transport.