ABSTRACT
The safety of dangerous rock has a decisive effect on the efficiency of highway operation. The rock mass and protective structures are aging and under accumulated damage because of the complicated mountainous hydrogeology, exploration of long-term field environment, and repeated loading or vibration of vehicles; thus, rockfall or collapse hazard is inevitable. For example, the collapse of Taiwan Formosa express in Xizhi, Keelung section, on 25 April 2010, causing the burial of two-way tines and complete traffic disruption, was due to the breakage of Dapu Bridge.
