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