1. Humphrey Institute of Public Affairs, University of Minnesota, 301 19th Ave S., Minneapolis, MN 55455, USA
2. Department of Civil Engineering, University of Minnesota, 301 19th Ave S., Minneapolis, MN 55455, USA
3. Active Communities/Transportation (ACT) Research Group, Humphrey Institute of Public Affairs, University of Minnesota, 301 19th Ave S., Minneapolis, MN 55455, USA
4. Active Communities/Transportation (ACT) Research Group, Environmental Design Building, University of Colorado, Campus Box 314, Boulder, CO 80309-0314, USA