Victor H. Torrey III’s scientific contributions

Statistical ranking models are employed to extract information from an historical database on the prioritization of maintenance and repair operations for embankment dams within the U.S. Army Corps of Engineers. This information is used to develop weighting functions that express the relative importance of general classes of maintenance and repair operations in an effort to implement a Function-Based Condition Indexing methodology. In particular, the weighting functions are used to convert the condition index vector [a representation of the condition of the embankment dam under several repair, evaluation, maintenance, and rehabilitation (REMR) objectives, one element per objective] into a condition indexing scalar (a representation of the overall condition of the embankment dam). Goodness-of-fit statistics are used to evaluate the ranking criteria models. The procedure is demonstrated on embankment dams for the REMR objectives of “Prevention of Surface Erosion” and “Collection of Performance Information” using the Automated Budget System (ABS) database of the Corps of Engineers. The statistical analysis indicates that physical parameters such a dam age and height have had a tremendous influence on the historical prioritizations for individual operations under the two REMR objectives studied even though these may not have been explicitly considered during the ranking process. Other important parameters such as reservoir size, fetch, downstream hazard, and economic effect of the dam should be investigated in the future to determine the weighting functions for the final version of the condition indexing system.

A total-systems approach is presented for the development of condition-indexing systems for aging civil engineering facilities that formalizes the necessary decision-making process. An application is given for embankment dams. A condition-indexing system is a tool that defines the physical state of a given facility or a portion thereof in terms of a numerical condition index. The index can be used as the criterion or as one among several criteria for prioritization of repair, evaluation, maintenance, and rehabilitation (REMR) expenditures among many similar systems. The proposed methodology will generate the essential elements of a condition-indexing system and includes the identification of specific objectives for REMR activities, the consideration of complex interactions between subunits of the facility, and the identification of critical system components. A condition-indcx vector is developed by considering the subunits of the facility repeatedly for the multiple REMR objectives. This vector can be converted into a scalar by applying weighting functions that describe the relative importance of each REMR objective.