1. Prof. of Civ. Engrg., Univ. of California, Berkeley, Calif.
2. Asst. Prof. of Engrg., Univ. of California, Los Angeles, Calif.
3. Sr. Engr., Dames & Moore, San Francisco, and Asst. Research Engr., Institute of Transportation and Traffic Engineering, Univ. of California, Berkeley, Calif.