1. Researcher, Dept. of Construction Management and Engineering, Univ. of Twente, P.O. Box 217, 7500 AE Enschede, Netherlands.
2. Associate Professor, Dept. of Construction Management and Engineering, Univ. of Twente, P.O. Box 217, 7500 AE Enschede, Netherlands (corresponding author).
3. Professor, Dept. of Construction Management and Engineering, Univ. of Twente, P.O. Box 217, 7500 AE Enschede, Netherlands.