Decision Support Model for Assessing Net Public Benefits of Reuse of Waste Materials in Highway Maintenance and Construction Projects

摘要

The state of Minnesota frequently receives requests from an outside source to consider accepting waste materials for reuse in highway maintenance and construction projects. The materials can include glass, roofing shingle tabs, shredded tires, coal ash, railroad ties, and taconite tailings. The Minnesota Department of Transportation (Mn/DOT) recently established a policy requiring that the use of waste material provide both short- and long-term public benefits. Mn/DOT also sought a framework to assess whether such benefits exist. Accordingly, a decision framework and decision support tool in the form of an electronic spreadsheet were developed, tested, and refined through the application of three case studies. The framework and decision support tool spreadsheet are described, and the results of one of the applied case studies are presented to illustrate the types of inputs required by the spreadsheet and the outputs produced. The spreadsheet is a very flexible tool that is able to account for a wide variety of materials and their placement in highways. It compares over a 20-year period the discounted present value of the incremental increase in highway maintenance and construction costs as a result of using taconite tailings in roads to the avoidable costs of disposal through transporting the waste and landfilling it or disposing of the waste material at the source where it is generated (e.g., a taconite mine).