1. Lect., Dept. of Civ. Engrg., Univ. of Nottingham, University Park, Nottingham, NG7 2RD, U.K.
2. Tech. Dir., Scott Wilson Pavement Engineering Ltd., 9 Faraday Build., Highfields Science Park, University Blvd., Nottingham, NG7 2QP, U.K.
3. Teaching and Res. Fellow, Dept. of Civ. Engrg., Univ. of Nottingham, University Park, Nottingham, NG7 2RD, U.K.