1. Professional Engineer, New York State Dept. of Transportation, POD 3-4, 50 Wolf Rd., Albany, NY (corresponding author).
2. Licensed Engineer, Swedish Rail Administration, 781 85 Borlänge, Sweden.
3. Professor of Technology, Dept. of Civil, Mining and Environmental Engineering, Luleaa Univ. of Technology, LTU SE-971 87 Lulea, Sweden.