Side-by-side prestressed concrete box-beam bridges have been and continue to be a popular choice in the state of Michigan and throughout the U.S. Various forms of deterioration have been identified specific to this type of construction. However, due to the nature of the design, only the bottoms of the beams and the exterior fascia beams are available for visual inspection. Fifteen bridges of varying ages were carefully selected and inspected for distress. Common forms of deterioration present in box-beam bridges were identified and presented in an inspection handbook. Finite element analysis were performed to assess box-beam designs that may cause future deterioration. Load ratings were performed to assess the impact of common forms of distress using the established AASHTO method as well as the box-beam specific finite element model. The results of this study produced an inventory of common forms of deterioration in side-by-side box-beam bridges and an understanding of the structural impacts of these distresses.