Chicago’s O’Hare International Airport tower at dusk.

O’Hare Modernization Program Completion Phase

One of the biggest construction projects in the country, at one of the world’s busiest airline hubs, transformed Chicago’s O’Hare International Airport from a system of intersecting runways to a modern parallel runway configuration. The $8.5-billion program, accomplished over the past decade, serves to reduce flight delays and increase airport capacity well into the future. The airport currently handles 80 million passengers and 867,000 flights annually.

An essential component of the modernization effort’s final phase was the addition of two new runways south of the main terminals, 11,245 and 7,500 feet long, and each able to accommodate large passenger aircraft. Their construction necessitated the relocation of 2.5 miles of Irving Park Road (IL-19), 12 acres of wetlands comprising the Bensenville Ditch, and a 2.5-mile stretch of mainline Union Pacific Railroad (UPRR) tracks. As Master Civil Engineer for the O’Hare Modernization Program’s Completion Phase, Gannett Fleming provided conceptual engineering design, design review, and coordination for runway construction and infrastructure relocations. The firm also served as Engineer of Record for construction of a centralized de-icing facility that provides efficient and organized plane de-icing away from the terminal gate areas of the airport.

What We Did

The new runways, as well as associated aircraft taxiways and utilities, were constructed in accordance with Federal Aviation Administration (FAA) requirements. Relocation work included coordinating horizontal and vertical alignments between the new runways and relocated facilities, adding a grade separation between IL-19 and the UPRR tracks, and designing a retaining wall to support the railway. The relocated tracks required construction of a new bridge over active Metra and Central Pacific Railroad lines as well as the installation of two signalized intersections. The relocated wetlands were carried beneath the railroad by tunneling four 12-foot diameter reinforced concrete pipes spaced 20 feet apart.

The team completed two intersection design studies and a location drainage study and obtained Illinois Department of Transportation (IDOT) approval to finalize the IL-19 relocation. The work was coordinated with planned IDOT projects nearby and designed to accommodate roadway expansion from four lanes to six.

Key Features

  • New runways increase airport operational capacity and reduce flight delays.
  • Centralized de-icing facility enhances efficiency for essential safety procedure.
  • Relocated roadway maintains travel route for 28,000 travelers daily.
  • Wetlands relocated in accordance with state environmental requirements.
  • Freight railroad moved with minimal disruption to railway operations.


  • Increased peak airport operational capacity by 50%.
  • Flight delay rate reduction by an estimated 79%.
  • Seamless coordination with plans for future airport expansion.


City of Chicago, Department of Aviation


Chicago, Ill.


Civil Engineering

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