The preservation of the state highway system and normal flow and safety of the motoring public is the statutory responsibility of state departments of transportation. The trucking companies hauling overweight and oversized loads apply for Special Hauling Permits for travel on state routes. The process of approving such superload permit applications is currently performed manually. This is a labor-intensive task, which can take a few days per application. To alleviate the problem, a knowledge-based expert system, called PERMIT_EXPERT, has been developed in the Microsoft Windows environment for handling of superload hauling permit applications. Knowledge representation is through decision trees and production rules. Since calculations of various rating factors require structural analysis, PERMIT_EXPERT is developed as a coupled expert system with access to an external structural analysis and bridge rating program. The knowledge base of PERMIT_EXPERT is acquired from design and operation guides of AASHTO specifications and the Ohio Department of Transportation and through interviews with experienced rating engineers. PERMIT_EXPERT can be used as a knowledgeable assistant by bridge rating engineers as well as for training new personnel.