Integrated, multi-attribute decision support system for the evaluation of underground utility construction methods.

摘要

The dissertation research work described herein is comprised of three primary objectives: (1) the development of a rehabilitation method selection software (TAG-R) for the National Association of Sewer Service Companies (NASSCO) and its subsequent validation and combination with TAG (a sister decision support system (DSS) software developed by the author in an earlier work) (2) the development of a social cost calculator (SCC) and its validation and (3) the development of a proposed framework for multi-segment optimization for construction methods selection using the tools developed in the first two objectives as well as additional project related data.The selection of a construction method involves many factors, which should be considered each time a new pipe segment needs to be addressed. This creates the need for a localized database containing technical data for the construction methods that are available for installation, replacement and rehabilitation of buried utilities. In addition to the database, a fully automated algorithm is needed for processing the project data, comparing it to the construction method databases, and identifying technically viable construction methods for the specific pipe segment under consideration. Each of these was accomplished with the developments of TAG-R, originally made commercially available through NASSCO on CD and now also being available through the TTC website in its full form, combined with TAG (a sister software developed in earlier work) at the web address http://138.47.78.37/tagrv2/>.The study of social costs and the benefit offered by trenchless technologies when compared with open cut construction methods has been investigated over the past 25 years by many researchers, with methodologies for estimating social cost elements and incorporating them in the bid process being examined. However, there is no algorithm that combined this work into a single, generic approach in the public domain. This created the need for a software capable of evaluating alternative construction methods based on project input and providing reliable calculations for multiple social cost categories including, (1) traffic delays and vehicle operating costs (2) pedestrian delays (3) noise pollution (4) dust pollution (5) air pollution (6) loss of parking revenues and, (7) pavement restoration. This was accomplished by codifying an algorithm, which uses established calculation methods, into a standalone software called Social Cost Calculator (SCC), which can evaluate up to two competing construction methods at a time.Once all methods deemed technically viable for a pipe segment were identified and their social costs determined, the most economical method can be selected by including the direct construction costs. However, there is a need to be able to evaluate multiple segments, since most utility projects involve more than a single pipe segment. This necessitated to the development of a framework for optimizing the method selection process for multiple segments. Once a method selection evaluation has been conducted for all of the segments on a given project, their direct cost and social costs are calculated for each combination of methods. The multi-segment analysis include additional parameters such as perceived risk, adjustment of the direct cost for the method service life and mobilization/demobilization cost, to determine the most economical method solution set for the project at hand.