The Iowa Department of Transportation is in the midst of a comprehensive redesign known as the I-80/I-380 Systems Interchange Project. Located in Johnson County, which is in the eastern central part of the state, the project is at the junction of Interstate 80, Interstate 380 and United U.S. 218, one of the busiest interchanges in the region. The infrastructure project has two goals: improve safety and expand capacity. Traffic in the area has grown and is projected to continue to increase. The roadways are not able to handle the amount of traffic, as there are regular slowdowns. By 2045, the average daily traffic count is projected to rise to 84,900 vehicles on I-80, 92,300 on I-380, and 61,100 on U.S. 218.

The traffic entering the interchange on a daily basis in 2017 was 90,000 vehicles and 15,000 freight trucks, and by 2020 the numbers grew to 100,000 vehicles and 17,000 freight trucks.

How will the traffic be impacted once the project is complete?

Over the next 30 years, models predict approximately 64 million fewer hours of traffic delays and the estimated typical trip will be 5 to 35 percent more reliable or more likely to arrive on time than is happening right now.

There are an inordinate number of crashes that occur around the interchange. While the accidents are primarily fender benders, serious crashes occur as well. Besides the safety component this brings up, it also serves to slow traffic. It’s expected that over a 30-year period, the new interchange will mean 745 fewer crashes and 82 fewer injury and fatal crashes.

The four loops that make up the interchange are being replaced with directional ramps. I-380 will be widened to six lanes with 12-foot shoulders from I-80, to approximately one mile north of the Forevergreen Road interchange.

U.S. 218/IA 27 will be widened to six lanes from I-80 to approximately 1.5 miles south of I-80. Interstate 80 will be widened to six lanes with 12-foot shoulders between Ireland Avenue and I-380. Interstate 80 will be widened to eight lanes from near I-380, east to near Coral Ridge Avenue. Additionally, auxiliary lanes will be included in some areas between interchange ramps to provide drivers more time to merge in or out of interstate traffic.

This is also a heavy bridge project as 21 new bridges are being constructed in various stages such that there are 36 design numbers associated with these bridges. Two other bridges are being widened. New pavement will be installed throughout the area.

On a project as large as this one, there are typically multiple events happening simultaneously. Making sure materials and equipment are in the right place at the right time requires foresight.

“Gaining project assess has been a challenge,” says Hugh Holak, a Resident Construction Engineer for Iowa DOT, whose responsibilities on the project include administering the contract and overseeing the inspection team.

While the project had the typical site restriction times regarding lane closures and when to bring material, “This project had a fairly extensive list of traffic dos and don’ts including lane closure time, and where you can gain access,” said Andy Stone, Project Manager for United Contractors, one of the joint general contractors on the project.

Besides the difficulties getting materials to the site, there was the issue of transporting projects within the project itself. “The contractor created a haul road in order to avoid traffic and more easily transport materials,” said Holak.

In the area around the interchange, there’s a creek. During construction, the team encountered some dirty sand for soils. The water table led to liquefaction issues that make building in the area difficult. “We installed drainage tile to keep the water table low enough to stabilize the ditch and used a rock key to stabilize the toe of the back slope,” said Holak. Wick drains were also used.

Another challenge related to construction occurred due to the grade changes. The large cuts and fills required extensive shoring. “We used sheet piles and temporary MSE walls to accommodate grade changes,” said Stone. “Doing the installation in limited space and with limited access, as well as the challenging soil conditions made it difficult to get an acceptable shoring design.”

To select a contractor for this design, bid, build, project, the Iowa DOT, used a special letting. Because of the complexity of the project and its schedule demands, a joint venture was selected. Besides the two general contractors – United Contractors and Cramer Bridges – 24 different subcontractors are involved. The winning team turned in the low bid.

Construction on the project began in the summer of 2017 and is expected to be complete in the summer of 2024. The project is on schedule so far and the team is hopeful the project will be completed on time. There have been obstacles to overcome.

“In the fall of 2019 and spring 2020, we were tracking behind due to the fall of 2018 and 2019 being very wet,” said Holak. “This meant we were unable to get things situated where we wanted to for winter work.” He notes the summer of 2020 was very dry, which allowed the team to catch up and came in on time at the end of the most recent construction season.

The financing has also impacted scheduling. Letting for the current project was delayed from July to December due to cash flow issues related to the pandemic. Holak said, “We were able to better coordinate the contracts and still expect the overall project timeline to be unimpacted.”

The construction budget for the project is $387 million and it is currently on budget. “When we formulate a budget, we do so knowing there will be changes in construction, so we appropriate money for the initial contract and for during construction,” said Linda Narigon, a Project Manager for Iowa DOT, who is providing high level oversight and oversees budget for this project.

Narigon noted issues have surfaced during construction that impacted the budget. The groundwater and subsurface issues noted above affected the design. Additional rock and tile and drainage were needed. “Our road estimates were high, but our bridge estimates have been low and everything evened out,” said Narigon.

Financing for the project has come via the federal, state, and local governments. The project also received a grant to develop a 3-D deliverable BIM model. This was a first in Iowa and its part of a research project for construction use of modeling,

The I-80/I-380 Systems Interchange Project will also enable commuters to experience better reliability as there will be enhanced capacity. With the expansion of the merge lanes, there will also be less weaving leading to fewer accidents. This infrastructure project has many positives for commuters.