O’Hare Airport Lead Tunnel Design – O’Hare 21

ABOUT THE PROJECT

The Chicago Department of Aviation (CDA)’s O’Hare 21 capital improvement program is the largest terminal expansion in the history of O’Hare International Airport.

ORDNext is the central terminal redevelopment phase of the program which includes construction of two  new satellite concourses (D/E),  the new O’Hare Global Terminal (OGT), which will replace Terminal 2, and the Consolidated Tunnel System.  The central tunnel system will run under taxiways and  convey utilities, baggage, and passengers from the O’Hare Global Terminal to the satellite concourses,

Atlas Engineering Group, Ltd. (Atlas) was responsible for the structural design for several retaining walls adjacent to both the Taxiway K&L Grade Separated Roadway (GSR) and A5/A6 GSR tunnel portals. Multiple wall types were designed including modular block, cast-in-place (CIP) concrete, soldier pile, CIP concrete on piles, cantilever sheet pile, and anchored sheet pile walls. Walls were designed to accommodate the aircraft surcharge loading from adjacent taxiways. Atlas was part of the design team for  Main Consolidated Tunnel connecting the OGT, to the satellite concourse D, and E. This design of the single level tunnel required detailed analysis of multiple loading conditions, including earth pressures, aircraft-induced loads, and seismic forces. Several structural design alternatives were evaluated including precast concrete roof slabs, a fully cast-in-place reinforced concrete tunnel section, and the usage of Grade 80 reinforcing steel for potential cost savings.

Atlas is also involved in the T3/T5 GSR Re-grading Project including retaining wall design with complex utility coordination and T5 Architectural Modifications Project including framing repairs and design.

Atlas also provided Phase III construction support for its scope, which included shop drawing/fabrication review and answering relevant RFIs.