Illinois I-39/US 20 Interchange Reconstruction Improves Corridor

Challenge: The I-39 and US 20 Interchange, located near Rockford, Illinois, within Winnebago County, was originally constructed in 1980. This interchange desperately needed upgrades and widening to accommodate the area’s growth and promote highway safety. The Illinois DOT (IDOT) focused on the reconstruction of this key interchange as part of the larger vision for improving the entire I-39 corridor.

Noteworthy areas of improvements I-39/US 20 included:

• Linden Road at Ramp bridge design (BD)
• Mulford Road at I-39/US 20
• Construction of five new bridges and a mechanically stabilized earth (MSE) wall constructed for the ramp BD bridge over US 20

Solution: HR Green provided construction engineering services for the I-39/US 20 Reconstruction. A project of this size, scope, and complexity requires management and inspection staff with technical expertise in many key construction disciplines and a keen understanding of the specific challenges associated with it.

Utilities + Partnerships

The larger IDOT I-39 Corridor Improvement project was managed by G.E.C. for IDOT. HR Green has built a trusting relationship with both IDOT and G.E.C., assisting with RFIs, submittal reviews, utility relocations, and overall coordination between IDOT, local agencies, and the connecting projects nearby.

In addition, HR Green has assumed the key positions on the I-39/US 20 Reconstruction and has utilized sub-consultants for bridge and roadway inspection. The aggressive project schedule periodically included working seven days per week, along with day and night shifts. The construction work impacting traffic along I-39 and US-20 was mostly completed at night to avoid delays for motorists during prime travel times.

Bridges + Structural Work

The project included a large amount of structural work as five new bridges are being constructed and an MSE wall for Ramp BD bridge over US-20; locations include:

• Ramp BD over US 20
• Ramp DB over Linden Road
• Ramp DA over Ramp BD
• Linden Road over Ramp BD
• Mulford Road over I-39/US20

All five bridges involved differing conditions, which included sub-structure improvements utilizing piling, caissons, pier construction, and installation of curved steel girders, standard steel girders, and PCC pre-stressed girders. The most complex structure was Ramp BD — the flyover bridge carrying southbound I-39 traffic across US 20, which included multiple piers and a complex steel girder system utilizing two box beams to interconnect the curved girders that spanned the long crossing from US 20 to I-39.

Roadway Design

Completing the reconstruction of an active interchange in an expedited timeframe while maintaining free-flowing traffic is a significant undertaking, and HR Green rose to the challenge. The project has included the construction of additional lanes on the ramps, which will provide a safer interchange experience for motorists traveling along this corridor. The use of continuous reinforced concrete (CRC) pavement will also create a long-lasting roadway and is a more cost-effective measure.

The roadway reconstruction also included over 65,000 cubic yards of rock excavation that was blasted, sliced, and hammered to allow for the new lanes of I-39. In addition to the CRC pavement work and rock excavation, the project included nearly one million cubic yards of earth excavation and placement of embankment throughout the project limits; and storm sewer improvements.

Benefit: The IDOT focused on the initial I-39/US 20 Interchange Reconstruction as part of its larger vision for the I-39 corridor. The successful completion of this first section benefits the community and public traveling the corridor and sets the stage for future corridor improvements.