1. Graduate Student Researcher, The Univ. of Texas at Austin, #1 Universtiy Station (C1761), 6.508, Cockrell Jr. Hall, Austin, TX 78712-1076. E-mail: jdl880@mail.utexas.edu
2. Graduate Student Researcher, The Univ. of Texas at Austin, #1 Universtiy Station (C1761), 6.508, Cockrell Jr. Hall, Austin, TX 78712-1076. E-mail: brendazhou@mail.utexas.edu
3. Associate Professor and William J. Murray Jr. Fellow, Dept. of Civil, Architectural and Environmental Engineering, The Univ. of Texas at Austin, #1 Universtiy Station (C1761), 6.9 E, Cockrell Jr. Hall, Austin, TX 78712-1076 (corresponding author). E-mail: kkockelm@mail.utexas.edu
4. Lecturer, Dept. of Urban and Environmental Policy and Planning, Tufts Univ., 97 Talbot Ave., Medford, MA 02155. E-mail: barbara.parmenter@Tufts.edu