1. Safe Transportation Research and Education Center, University of California, Berkeley, CA 94720-4800, USA
2. Department of Statistics, Texas A&M University, College Station, TX 77845, USA
3. College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77845, USA
4. Civil Engineering Department, University of Mississippi, Oxford, MS 38677, USA
5. Arcadis U.S., Raleigh, NC 27615, USA