1st Avenue & I-80 Interchange

Diverging Diamond Interchange
The Iowa Department of Transportation plans to reconstruct the interchange at I-80 exit 242 and 1st Avenue with a diverging diamond interchange (DDI). The Iowa DOT is the lead agency on this project.

The existing interchange at I-80 exit 242 is the original configuration constructed in the 1960s when I-80 was built through Iowa. The new diverging diamond interchange will provide safety improvements and is designed to handle projected traffic volumes.

I-80 1st Ave Diverging Diamond IDOT

About the Project
The prime contractor is Peterson Contractors, Inc., of Reinbeck, Iowa. The Iowa DOT is administering and inspecting the project.


  • The project had a September 2022 DOT letting.
  • Two trail closures of the 1st Avenue Trail where it crosses I-80 are scheduled for October 24-28 and November 7-11, 2022. The trail closures allow for construction of temporary pavement in preparation for the start of major construction in spring 2023.  
  • There will be intermittent lane closures on 1st Avenue, one direction at a time, from October 24 to November 18, 2022.
  • Major construction work will begin late March/early April 2023, with the demolition and reconstruction of the easterly (northbound) 1st Avenue bridge over I-80. 1st Avenue traffic will be reduced to one lane in each direction, with northbound traffic shifted onto the westerly (southbound) 1st Avenue bridge.
  • The road and bridge work is expected to be substantially complete by spring/summer 2025.
  • Final landscaping and related work should be complete summer/fall 2025.

Traffic & Pedestrian Impact

  • The project will utilize staged construction, including temporary pavement and temporary traffic signals. 
  • One lane of traffic will be maintained in each direction on 1st Avenue at all times.  
  • After the 1st Avenue Trail closures in October and November 2022, pedestrian access along 1st Avenue over I-80 should not be impacted again for the remainder of the project.


  • Diverging diamond interchange design eliminates the left turn phase at signalized intersections. This reduces overall traffic delay while also providing a significant safety improvement since left-turning traffic is no longer crossing opposing traffic lanes.
  • New grade-separated trail with underpasses and a trail bridge over I-80.
  • New 1st Avenue bridges accommodate the potential future widening of I-80.
  • New, signalized intersection to serve Iowa River Landing Place and the Magellan Terminal. 
  • New stormwater management practices, traffic signals, roadway lighting, and aesthetic treatments. 

The project is funded in part by a $20 million U.S. Department of Transportation BUILD grant awarded to the City of Coralville and transferred to Iowa DOT,  with the remaining costs covered by the Iowa DOT.

Learn More
Iowa Department of Transportation
Iowa DOT project website

Watch Video: Navigating the Diverging Diamond Interchange