The Illinois Department of Transportation (IDOT)’s new Interstate 74 (I-74) bridge over the Illinois Central Railroad (ICRR) and Oak Street is an example of efficient design, overcoming the effects of global challenges and innovative solutions to improve traffic safety throughout the region.
As a major component of the National Highway System, I-74 carries a large traffic load of over 63,000 vehicles per day. The original I-74 bridge consisted of two independent superstructures, totaling 725 ft long. The bridge also passes over two Amtrak tracks, 16 ICRR tracks and Oak Street.
When the bridge was identified as structurally deficient, IDOT announced its plans for replacement. To keep commuters moving, EXP designed a new bridge to connect the region and improve operations along this important portion of the state’s interstate system.
Preliminary engineering and design
During the preliminary engineering phase, EXP evaluated the steel structure for reuse, reconstruction and replacement. The selected plan included a replacement of the bridge with reuse of some of the existing substructure. During the design process, EXP provided bridge type, size and location plans, roadway plans, pre-final structure plans and final structure plans.
The new I-74 bridge consists of two separate structures with a total length of 725 ft. The four-span bridge has new safety enhancements including high-load multi-rotational bearings that support an increased load and a high-friction surface treatment that decreases the likelihood of traffic accidents.
EXP evaluated maintenance of traffic plans to reduce disruptions to vehicular traffic and worked with ICRR and Amtrak to coordinate the bridge replacement with railyard operations. These efforts helped to achieve a reasonable construction schedule and sequence of work, minimize traffic delays and limit additional construction costs. These coordinated efforts positioned the construction team to replace one structure at a time, leaving the other structure available to vehicles in both directions of traffic.
By carrying out these critical design and planning services for IDOT, EXP designed a new bridge to support a key piece of infrastructure for the National Highway System.
Bridge Design, Bridge Inspection, Structural, Civil