The addition of Light Rail Trains (LRT) to the Homer M. Hadley Memorial Bridge, the widest floating bridge in the world located in Seattle, Washington, is currently in its design process. The design team has concluded that a transition Track Bridge (TB) is necessary to accommodate large movements induced by the floating bridge in relation to the fixed approach structures and to provide reliable LRT service along the I-90 corridor. Dynamic train-structure interaction analysis was required to evaluate the TB performance and ride quality. A high fidelity finite element model of the bridge was developed along with two TBs. Each TB has been designed with 34 double-concave Friction Pendulum Bearings (FPBs) supporting bearer bars at both ends. The FPB model includes bottom and top plates and a slider in between, all modeled with solid elements. Simulation of frictional contact interaction between the plates and slider allows limited transverse movement of the rail under moving train loads. In addition to numerical analysis, component and full scale tests have been planned to examine the TB kinematics as well as FPB behavior. This paper presents a unique multi-scale FE analysis of a train-structure interaction system which includes detailed model of TBs incorporated in the global model of the floating bridge.