Calculation of load-carrying capacity of old railway masonry arch bridges as crucial infrastructures is one of the vital issues in the railway industry. The field test of the 2PL20 bridge reveals important properties such as the initial stiffness and cracking pattern, but the ultimate capacity of the bridge under static loading was not achieved due to the field limitations. Therefore, the present study aims to predict the total nonlinear response of the 2PL20 bridge up to the failure status. All the geometrical characteristics of the 2PL20 bridge are modeled precisely and the failure state is predicted using the three-dimensional nonlinear finite element analysis. Moreover, to determine the load-carrying capacity of the 2PL20 bridge, the behavior of materials is regarded nonlinearly in which the Williams and Warnke and the Drucker-Prager failure criteria are taken into account for concrete and soil materials, respectively. To obtain precise results of ultimate capacity of the 2PL20 bridge under field test, the vertical and horizontal displacements of the crown on the northern span are chosen as the calibration criterion and, consequently, the vertical and horizontal load-deformation curves are verified based on the field test results. The obtained results indicate that the load-carrying capacity of the 2PL20 bridge equals 8880 kN under the static field test. Finally, the calculated safety factor is equal to 3.2 and increasing axial load up to 35-ton is admissible based on UIC 776-1 for a 25-ton axial load.
