In Ethiopia, there is a large number of reinforced concrete bridges constructed during the 1950s that are still in service today. However, with the increase in vehicle axle loads and traffic flow due to urbanization and socio-economic development, these old bridges may no longer have the capacity to safely support the current loads. Furthermore, the lack of comprehensive design and construction records for many of these bridges makes evaluating their current condition and capacity challenging. This study focused on assessing the load carrying capacity and identifying structural defects of the Abay Bridge No. 4, an old reinforced concrete bridge located in Bahir Dar, Ethiopia. An efficient finite element model was developed using Abaqus/CAE 2017, incorporating information from historical documents, field inspections, material testing, and design codes from the time of the bridge's construction in 1962. The finite element analysis, which simulated moving tire loads on the bridge deck, was used to load rate the bridge for the Ethiopian Road Authority's legal vehicle loads. The results showed that the bridge has enough strength to withstand the legal loads, with reserve capacities of 27%, 74%, and 75% for legal loads 1, 2, and 3, respectively. However, the study also identified several defects and distresses during the field inspection that could contribute to further deterioration of the bridge if not properly maintained. This research demonstrates the effectiveness of using finite element analysis for evaluating the capacity of existing bridges without comprehensive design records. The findings can help bridge owners and managers develop appropriate maintenance and rehabilitation strategies for aging infrastructure, ensuring the continued safe use of these critical transportation assets. Keywords: Bridge, Assessment, Load Rating, Finite Element Analysis