Due to the environmental and financial benefits of thermoplastic materials as mentioned in literature and being a viable green solution, a nonlinear finite element analysis was conducted to study the behavior of thermoplastic materials of the No. 3 Fort Eustis railroad bridge using ABAQUS in terms of deflection, stress, and vertical forces at critical locations. Six models were simulated. These models were evaluated under GE 80-Ton switcher at 8 km/h (kph) speed and GP 16-120 Ton locomotives at speeds of 8, 24, 40, 56, and 80 kph. The models were validated against experimental results available in the literature. The models studied the effect of train speed on the deflection profile, flexural stress profile, vertical force profile, and stress profile along the bridge as well as the stress profile along the section. Based on the simulated models, it is clearly shown that the thermoplastic material has lower deflection and stress than wood; higher speeds resulted in lower stress and deflection. Based on this study, thermoplastic material can be considered as a good alternative because of its performance in terms of stress, vertical force, and corresponding deflection.