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Indianapolis Airport Utility Connector Tunnel


Indianapolis Airport Utility Tunnel


Rather than build a new energy plant to serve the new Midfield Terminal at Indianapolis Airport, it was determined that an approximately 1-mile-long utility corridor from the existing central energy plant to the new terminal, including a 2,016-foot  tunnel under an active runway and two taxiways, was the best solution. The utility corridor and tunnel carry high-temperature hot water, chilled water, plant-terminal communications and conduit for 13.8-kV electrical distribution. WSP USA provided the Indianapolis Airport Authority with project management and coordination; conceptual design of alternatives; civil, mechanical and structural engineering; subsurface exploration and geotechnical engineering; tunnel design; preparation of plans and specifications; and construction administration.

Based on our specifications, the contractor selected an earth pressure balance tunnel boring machine. We developed an extensive geotechnical instrumentation program to monitor the deformations of the tunnel and the ground as construction proceeded, with review levels and alert levels pre-established to provide a means of managing the risk associated with loss of ground. Design for thermal expansion of the high-temperature hot water lines required special detailing where the thermal utilities transition from the tunnel to the trench installation.

Tunnel construction proceeded without disruption to air traffic and was completed in November 2006. Settlement of the runway and taxiways was less than 0.25 inches, and well within the tolerable limits established for the project. Utilities were placed in service in late 2007, and the system was operational as of January 2008.

The project was named 2007 Project of the Year by Trenchless Technology magazine.