1. Senior Lecturer, Dept. of Civil Engineering, Faculty of Engineering, Univ. of Peradeniya, Peradeniya 20400, Sri Lanka.
2. Distinguished Professor of Civil Engineering and Research Director, Centre for Geomechanics and Railway Engineering, Univ. of Wollongong, Wollongong City, NSW 2522, Australia; Director, ARC Training Centre for Advanced Technologies in Rail Track Infrastructure, Univ. of Wollongong, NSW 2522, Australia (corresponding author).
3. Research Fellow, Centre for Geomechanics and Railway Engineering, Univ. of Wollongong, Wollongong City, NSW 2522, Australia.