Bridge constructions are developing rapidly as they are necessity in the transport network. The Passenger Boarding Bridge (PBB) provides passengers with means to embark and disembark a ship through weather protected tunnels. It is obvious that the endurance and safety of such structures are of paramount importance. It has been shown that forces and moments at three-tunnel boarding bridge supports were high in the critical cases, as well as stresses in pins and lugs. The aim of this research is to analyze crack propagation in the damaged supporting part of the PBB. After determination of critical components to demonstrate how dangerous the appearance of the crack could be and to evaluate the fatigue life of the damaged supporting part, numerical simulations based on the improved finite element method (FEM) were carried out. To do this, the determination of actual loads was conducted with special consideration. The predicted number of cycles to complete failure was low, indicating the fact that special attention has to be paid on the design of PBB's critical supporting components.