1. Research Fellow, Univ. of the West of England, Coldharbour Ln., Bristol, Avon BS16 1QY, U.K. (corresponding author).
2. Research Associate, Dept. of Engineering, Univ. of Cambridge, Trumpington St., Cambridge, Cambridgeshire CB2 1PZ, U.K.
3. Laing O’Rourke Reader, Construction Engineering and Technology, Dept. of Engineering, Univ. of Cambridge, Trumpington St., Cambridge, Cambridgeshire CB2 1PZ, U.K.
4. Laing O’Rourke Senior Lecturer, Construction Engineering and Technology, Dept. of Engineering, Univ. of Cambridge, Trumpington St., Cambridge, Cambridgeshire CB2 1PZ, U.K.; Visiting Lecturer, Qatar Univ., P.O. Box 2713, Doha, Qatar.
5. Laing O’Rourke Professor, Construction Engineering and Technology, Dept. of Engineering, Univ. of Cambridge, Trumpington St., Cambridge, Cambridgeshire CB2 1PZ, U.K.