RISK IDENTIFICATION EXPERT SYSTEM FOR METRO CONSTRUCTION BASED ON BIM Limao Zhang, *Xianguo Wu, Lieyun Ding, Yueqing Chen Huazhong University of Science and Technology 1074 Luoyu Road Wuhan, China, 430074 (*Corresponding author: wxg0220@126.com) Miroslaw J. Skibniewski University of Maryland, College Park 1188 G.L. Martin Hall Maryland, USA, 20742