6Olhoeft G R, Selig E T. Ground penetrating radar evaluation of railway track substructure conditions [ C ] l// 9th International Conference on Ground Penetrating Radar, 2002:48- 53.
7M. L. Filograno, P. Corrcdera, M. Rodrtguez-Plaza. Real Time Mo- nitoring of Railway Traffic Using Bragg Grating Sensors [ C ] // Proceedings of the 2010 Joint Rail Conference, 2010 : 1 - 8.