**8. Acknowledgment**

This research was partially supported by Eusko Trenbideak - Ferrocarriles Vascos (a railway company from the north of Spain), Innovate and Transport Engineering (a railway technology provider), the Ministry of Industry, Tourism and Trade of Spain under the Avanza funding program (Grant TSI-020501-2008-148), and the Basque Country Government under the Euskadi+09 funding program (Grant UE09+/70). This support is gratefully acknowledged.
