1. P.E.
2. P.E., Members, ASCE
3. Coordinator and Transp. Engr. Dir., North American Free Trade Agreement Intermodal Transportation Laboratory, Burges Hall, Room 414, Univ. of Texas at El Paso, El Paso, TX 79968. E-mail: liu _c _c@ yahoo.com
4. Prof. Emeritus of Civ. Engrg., Dept. of Civ. Engrg., Univ. of Texas at Austin, Austin, TX 78712.