Coordination Critical in ATL Tunnel Extension
Coordination Critical in ATL Tunnel Extension
Abstract
August 30, 2022 Derek Lacey KEYWORDS Airport Construction / infrastructure / tunnels Order Reprints No Comments Extending the tunnel for Hartsfield-Jackson Atlanta International Airport's Plane Train, the airport's automated people mover, is a juggling act of intense coordination among stakeholders, requiring careful navigating of underground foundations and utilities supporting the world's busiest airport. Photo courtesy Brian Crumb Shaft work on the tunnel extension began in May 2020, with horizontal tunnel excavation starting in October 2020 and wrapping up in January. For more than a year of tunnel excavation, the engineer, contractor and sometimes an owner's representative would meet for a required excavation support meeting at 7 a.m. at the tunnel face, examining the conditions and deciding on that day's length of excavation and required support type. "So being able to see just how much coordination-there are a lot of really cool things behind the scenes."The tunnel extension had to navigate multiple nearby foundations, including for the airport's SkyTrain, and MARTA.Image courtesy McMillen Jacobs AssociatesShort Tunnel, Tall ChallengeIt's point A to point B at a certain elevation, and that was the challenge, Murray says. "It's a short tunnel but it has all the complexities of a really big tunnel project."The tunnel crosses about 23 ft from foundations for the airport's SkyTrain, which carries passengers from the baggage claim area to the Gateway Center and Rental Car Center underneath the MARTA station and around 5 or 6 ft from its elevator and the hydraulic piston that powers it. "There's an elevator right between two tunnels. On the south wall of the elevator, you can see the north wall of the south tunnel."Beyond that, the tunnel moves underneath the terminal building foundations and splits into two sections. Normally, a curve with a large enough radius would accommodate the turn, but in this case, the diameter of the tunnel changes three times to make a portion of the tunnel large enough to fit the train through the curve.
