1. Professor and Director, (Tsinghua-Gammon) Construction Safety Research Center, School of Civil Engineering, Tsinghua Univ., Beijing 100084, China (corresponding author).
2. Master Student, School of Civil Engineering, Tsinghua Univ., Beijing 100084, China.
3. Chief Consultant, Occupational Safety and Health Council, 19/F., China United Centre, 28 Marble Rd., North Point, Hong Kong.