Minneapolis’ light rail transit (LRT) system came closer to completion on 26 October, when the second of two 2.9km tunnels under Minneapolis-St. Paul International Airport broke through. The 6.7m diameter, 500t Herrenknecht EPBM emerged from the north-bound tunnel just before sunrise.
HNTB Corporation designed the twin LRT tunnels for the Minneapolis-St. Paul Metropolitan Airports Commission and provided resident engineering and inspection services. The contractor was a Joint Venture between Obayashi Corporation and Johnson Brothers Corporation.
An EPBM was used to minimize disruption to airport facilities and ongoing operations. Movable work zones were also established on the airfield to keep aircraft off specific taxiways and taxilanes when the TBM was boring below.
The southbound tunnel was completed in April 2000, and the project’s completion is scheduled for August 2004. The LRT tunnels are the largest to be bored directly under an active US airfield and will be the longest in Minnesota.
