1. Ph.D. Student, Centre for Geomechanics and Railway Engineering, Univ. of Wollongong, Keiraville, NSW 2522, Australia.
2. Distinguished Professor of Civil Engineering, Director, Transport Research Centre, Univ. of Technology Sydney, Ultimo, NSW 2007, Australia; formerly, Director, Australian Research Council (ARC) Industrial Transformation Training Centre, ITTC-Rail, Univ. of Wollongong, Keiraville, NSW 2522, Australia (corresponding author).
3. School of Civil Engineering, Univ. of Leeds, Leeds LS2 9JT, UK; formerly, Centre for Geomechanics and Railway Engineering, Univ. of Wollongong, Keiraville, NSW 2522, Australia.