Elgin O'Hare Western Access (EOWA) Interchange

The Elgin O’Hare Western Access (EOWA) Interchange is the centerpiece of the Illinois Tollway’s ongoing $3.6 billion EOWA program which aims to improve connections between O’Hare International Airport and surrounding communities, reduce travel times and ease local road congestion. As a critical component of this transformative initiative, Stanley Consultants designed a key tri-level interchange that will connect Illinois Route 390 with the new I-490, creating vital access to the west side of O’Hare International Airport. Delivered in multiple construction packages at varying stages of completion, the project highlights innovation in engineering and infrastructure development.

The scope of the project includes new high-capacity ramps, consisting of six flyovers and nine new ramp bridges, as well as local road relocations, new retaining walls and culverts, extensive earthwork and soil treatment. It also required complex stormwater detention systems, the relocation of Willow Creek and its floodplain and the installation of traffic signals, signing, lighting, tolling and intelligent transportation systems. Additional elements included major utility relocations, the relocation of airport navigation aids and runway approach lighting systems and extensive traffic control measures. The system interchange is within O’Hare right-of-way and airspace and is constructed over two Class I railroads, local roads and major utilities requiring significant stakeholder coordination and approvals.

Stanley Consultants has completed the design of two critical flyover bridges at the interchange, addressing complex operational and spatial requirements. Both bridges were curved structural steel plate girder design with the longest being the tri-level bridge that spans 1,173 feet over I-490, Union Pacific Railroad, Central Pacific Railroad and York Road.