Fox River Bridge

Stanley Consultants provided engineering services for the design and replacement of the Jane Addams Memorial Tollway (I-90) Bridge over the Fox River. This $95 million project transformed a 15-span, 6-lane bridge into a modern, 8-lane, twin structure spanning 1,315 feet with full-width shoulders.

The new bridge was designed to reduce maintenance, minimize environmental impact, and extend its lifespan to 75–100 years. To maintain traffic flow for over 100,000 daily vehicles, Stanley Consultants incorporated a unique accelerated bridge construction technique. The design allowed new piers to be built under the existing bridge in their entirety prior to the staged bridge removal above. Construction included innovative use of an overhead gantry system to place 100-ton concrete beams, avoiding lane closures and shortening the schedule by six months.

Value engineering played a key role in the selection of the 168-foot bulb-T beams, which were among the longest in the state at the time. By specifying longer spans, over half the number of piers was required, which not only reduced labor costs but also minimized environmental disruption. Fewer piers resulted in less impact to aquatic life, recreational boat traffic and the sensitive forested fen surrounding the bridge.

The bridge incorporated stainless steel rebar to extend deck life, reducing long-term maintenance. Three expansion joints, all accessible from the ground, replaced the previous eight over land and water, improving accessibility. A separate pedestrian, cyclist and vehicle maintenance bridge beneath the tollway enhanced connectivity and maintenance access.

This project exemplifies how innovative design and value engineering can address traffic, environmental and maintenance challenges while meeting modern infrastructure needs.