An old multi-plate arch bridge (arch bridge) was built at a busy mining site for mine transportation in Western Australia in the early 1970s. After operation for more than 30 years, large deformations were noticed at the openings of two steel plate arches out the four at one side of the bridge. Site survey and inspection were carried, showing some corrosion and large deformation at the eastern end of the middle two arches of the bridge. This paper presents a simplified 2D finite element analysis (FEA) for predicting and evaluating the excessive deformation of the aged plates of the bridge. The finite element analysis results are consistent with the survey data for the deformed shape. It is found that the local failure was mainly caused by inadequate engineering design of skewed bridge a structure under the heavy traffic loads from iron ore mining trains on top of it.