1. Research Associate, Centre for Geomechanics and Railway Engineering, ARC Industry Transformation Training Centre for Advanced Rail Track Technologies, Faculty of Engineering and Information Science, Univ. of Wollongong, Wollongong, NSW 2522, Australia.
2. Distinguished Professor, Research Director and Foundation Director, Civil Engineering, Centre for Geomechanics and Railway Engineering, ARC Industry Transformation Training Centre for Advanced Rail Track Technologies, Faculty of Engineering and Information Science, Univ. of Wollongong, Wollongong, NSW 2522, Australia (corresponding author).
3. Professor, Dept. of Civil, Environmental and Geomatic Engineering, Faculty of Engineering Science, Univ. College London, London WC1E 6BT, UK.