This thesis document was issued under the authority of another institution, not NPS. At the time it was written, a copy was added to the NPS Library collection for reasons not now known. It has been included in the digital archive for its historical value to NPS. Not believed to be a CIVINS (Civilian Institutions) title. All original paper copies missing. Best digital copy available. A diskette is located at DKL-119, call number N483. The development of a prototype knowledge-based expert system to assist safety analyses of short term, trench excavations on light commercial construction projects is presented. Background information for trench excavation hazards, OSHA safety compliance regulations, in-the-field soils analysis techniques, timber shoring design, and expert system development is introduced. Detailed discussion of the design and construction of a knowledge base for the safety analyses of short term trench excavations is included along with the methods involved in loading the knowledge base onto an expert system shell. http://archive.org/details/sftychefaconsult1094541619 U.S. Navy (U.S.N.) author. Approved for public release; distribution is unlimited.