1. Highway Safety Research Center, University of North Carolina, 730 Martin Luther King Jr. Blvd, CB 3430, Chapel Hill, NC 27599, USA,
2. Civil and Environmental Engineering Department, Old Dominion University, 135 Kaufman Hall, Norfolk, VA 23529, USA,
3. Carolina Transportation Program, University of North Carolina, CB 3140 New East Building, Chapel Hill, NC 27599, USA,