1. Asst. Prof., Dept. of Civ. Engrg., Univ. of Nebraska-Lincoln, W348 Nebraska Hall, Lincoln, NE 68588-0531. E-mail: akhattak@unl.edu
2. Asst. Prof., Engrg. Profl. Devel., Univ. of Wisconsin-Madison, 432 N. Lake St. #713, Madison, WI 53706. E-mail: knapp@epd.engr.wisc.edu