This study of Improved Load Rating Procedures for Deteriorated Steel Beam Ends with Deteriorated Stiffeners was undertaken as part of the Massachusetts Department of Transportation (MassDOT) Research Program. This program is funded with Federal Highway Administration (FHWA) State Planning and Research (SPR) funds. Through this program, applied research is conducted on topics of importance to the Commonwealth of Massachusetts transportation agencies. The national highway system consists of approximately 46,000 (1) structurally deficient bridges, with corrosion as a common cause for steel viaduct deterioration. This condition can be primarily attributed to malfunctioning deck expansion joints, which fail to prevent water or deicing mixtures from penetrating into the bearing area. The buildup of this runoff triggers a corrosive process that significantly varies in topology and intensity, leading in many cases to severe section loss that affects the residual bearing capacity of the beam and, consequently, of the whole bridge. This research focuses on simple span girders with plate girders and uses real corrosion data to assess the current bridge manual procedures.