An Accelerated Construction Project That Included the First Building Information Modeling Design Pilot for the Iowa DOT

One of the busiest interchanges in Iowa is now accommodating an increase in traffic, providing more reliability for drivers and improving a vital link for carriers and cargo following a large-scale reconstruction.

The I-80/I-380 System Interchange near Coralville and Iowa City, at the junction of I-80, I-380 and U.S. Highway 218, had become functionally obsolete due to increased traffic over the years since constructed.

The effort began to replace the interchange in 2017 with HDR providing construction management and general engineering consultant services to the Iowa Department of Transportation.

As part of the massive redesign, I-80 was widened to eight lanes, I-380/U.S. Highway 218 to six lanes and four loop ramps on the cloverleaf interchange were replaced with directional ramps. Other improvements included the construction of 26 bridges, removal of 80 lane miles of old pavement and paving of 113 new lane miles, resulting in an increase of 33 lane miles to the highway system.

Managing Traffic and Safety

One of our primary roles during construction was managing and monitoring day-to-day traffic flow in a small project area, which often saw upward of 90,000 vehicles and 15,000 trucks daily.

The team helped manage onsite traffic operations with the installation of cameras to monitor traffic flow. Dynamic message signs informed drivers of impending closures and other important announcements. Road sensors stationed around the project transmitted real-time traffic conditions back to the Iowa DOT Traffic Management Center. Adaptive smart signal technology was also added along a primary detour route to recognize traffic movement and change the traffic signal timings as needed.

Communicating anticipated and unanticipated traffic changes was important to maintaining broad public support for the reconstruction of the interchange. Our team worked together with the Iowa DOT on a public relations plan that included email, social media, and project website updates that kept stakeholders informed about construction updates and planned closures and detours. The plan also included direct outreach to businesses near the project area.

Our GIS experts and traffic engineers worked with local police and first responders throughout the interchange reconstruction to provide advance notice of planned closures and detours to local response teams, and to continuously update traffic incident management plans and maps to align with progress of the project. We also collaborated with Iowa State Patrol and media organizations to roll out a “Move Over” operation within the construction area to help educate the public on the state’s law to move over and slow down during traffic incidents.

Building Information Modeling

The I-80/I-380 System Interchange Reconstruction Project was part of a pilot project to study the advantages of using building information modelling on a highway bridge project, the first in Iowa. As the engineer of record for the project, we created BIM models for three complex steel plate girder bridges instead of traditional 2D plan sheets. One bridge was chosen by Iowa DOT to be built using the 3D BIM model as the legal document.

These digital models provided advantages in design and beyond. Contractors and fabricators were able to visualize complex details, such as the highly congested reinforcement cages within the bridge piers. They were also able to extract dimensions and other element properties directly from their tablets in the field, eliminating restrictions on predefined section cuts provided in traditional 2D plans. To enhance its use for future asset management, the model can be updated to incorporate final plans and link to critical construction documents such as product specifications, material certifications and construction photos.

Accelerating Construction

The reconstruction of the interchange was accelerated by two years with the award of a $50 million Infrastructure for Rebuilding America grant that HDR helped the Iowa DOT pursue and obtain. The shortened timeline is estimated to have directly saved the project $25 million.

We supported Iowa DOT with updating the construction staging design to better streamline the construction schedule. Our team worked with designers to revise the construction phasing so multiple work areas could overlap at the same time, creating opportunities for crews to provide continuous work on the project. This effort ultimately reduced the client’s risk while contributing to the opening of the interchange three months ahead of schedule.