Applications to reuse materials or reduce “the need” for new materials, and subsequently reduce energy, can take on a multitude of forms. By reducing energy to construct the highway networks, owners can benefit environmentally and economically in the long term. A collective effort, jointly by government and industry, to reduce and reuse highway construction materials can have a positive effect on the environment. The Nova Scotia Department of Transportation and Public Works (NS TPW) called a tender in July 2007 to replace a corrugated steel tunnel (CST) crossing Highway 101 near Windsor, Nova Scotia. The new concrete arch structure was stipulated as “Design-Build”, allowing the contractor to use innovative construction techniques, acceptable to NS TPW, to provide a cost effective structure replacement. This paper will describe the geotechnical analysis, approval and processes used to reduce the volume of foundation excavation for a new Bishopville Road arch tunnel. It will demonstrate the foundation improvement design did not adversely affect the structural integrity of the new structure. Survey data taken before, during and after final construction of the arch will illustrate the foundation settlement was well within design limits. The proven results of this case study show that geotechnical analysis of the “in-situ material” along with controlled construction practices can save backfill replacement costs, energy, and emissions to the environment.
