1. Postdoctoral Fellow, Civil and Environmental Engineering Dept., Univ. of Waterloo, Waterloo, ON N2L 3G1, Canada.
2. Graduate Student, Management Sciences Dept., Univ. of Waterloo, Waterloo, ON N2L 3G1, Canada.
3. Professor, Civil and Environmental Engineering Dept., Univ. of Waterloo, Waterloo, ON N2L 3G1, Canada (corresponding author).