1. Swedish Nat. Rd. Admin., Constr. and Maintenance, Div. of Business and Engrg. Devel., Box 4018, SE-171 04 Solna, Sweden. E-mail: fredrick.lekarp@vv.se
2. Prof., Div. of Hwy. Engrg., Royal Inst. of Technol., SE-100 44 Stockholm, Sweden.
3. Sr. Lect., Dept. of Civ. Engrg., Univ. of Nottingham, University Park, Nottingham NG7 2RD, U.K.