Los Angeles International Airport (LAX) is being redeveloped to accommodate a greater number of larger aircraft in a modernization program aimed to provide unrestricted operations of future large aircraft. More than a dozen trenchless utility installations have been completed by three separate contractors within the project limits through similar ground conditions. These tunnels have been excavated under active terminals and taxiways with low cover, and under footings with access shafts next to the terminal buildings in some cases. Trenchless installation of the utilities allowed for terminal gates and taxiways to remain in use with minimal impact to airport operations. Tunneling technologies utilized include horizontal auger boring, guided auger boring, directional drilling, and open-shield pipe jacking through running sands above the water table. Settlement was a major concern because of possible indirect costs of affecting operations at the sixth busiest airport in the world. This paper presents project experience from the 18-inch (457 mm) through 54-inch (1,372 mm) tunnel drives relating to: equipment performance, instrumentation and monitoring, airport worksite logistical issues, resulting settlement, and lessons learned.
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