“The Iowa Department of Transportation is more than two-thirds of the way through the process of reconstructing Interstate 80, Interstate 29, and Interstate 480 in the Council Bluffs/Omaha metropolitan area,” says Scott Schram, District Engineer with the Iowa Department of Transportation.
The latest efforts of this multi-year program revolve around the reconstruction of the interchange at I-29, I-480 and West Broadway.
“This $179 million project was developed to address capacity needs, improve safety, and improve functional design issues at this location and at adjacent interchanges at 41st Street, North 35th Street, Avenue G and 9th Avenue,” Schram says.
The larger Council Bluffs Interstate System Improvement Program is upgrading interstates and highways originally built in the 1950s and 1960s that no longer met design standards and lacked the capacity to efficiently carry current and future vehicle traffic.
Approximately 42,000 vehicles travel on I-29 daily and 56,000 on I-480. That volume is expected to increase by 2040 to 52,000 on I-29 and 63,000 on I-480.
“It will also enhance travel to and from I-29 and I-480 by eliminating left side entrance and exit ramps, and a sharp curve on I-29,” explains Mark Pohlmann, consultant HDR’s Program Manager since 2018 in Council Bluffs. “This will decrease driver lane changes and consolidate numerous entrance and exit ramps.”
Crews are adding two new arterial frontage roads, additional lanes on an approximately 2-mile segment of I-29, four new elevated system interchanges connecting I-29 and I-480, 12 new bridges that carry I-29 over four different surface streets, and several retaining walls to decrease the overall footprint of the interchange – all while avoiding significant right-of-way acquisition.
Multiple partners provided elements of project design. Iowa DOT designed traffic signs; HDR, the intelligent transportation system, lighting and adaptive traffic signals; HNTB of Kansas City, Missouri, the bridges, roadway and storm sewer; and HR Green of Cedar Rapids, Iowa, provided additional bridge design.
For the Mechanically Stabilized Earth (MSE) retaining walls, Ames used intermediate foundation improvements to increase the bearing capacity in the low-bearing soils. The project incorporated several design aesthetics into the MSE wall surfaces, bridge columns and bridge barriers.
“These aesthetic treatments enhance the look of the system interchange and contributes to the ‘gateway entrance’ to Council Bluffs,” Pohlmann reports.
Several stormwater detention areas were incorporated to help manage stormwater runoff during significant rains.
Coordination remains critical to the success of the project.
“Construction takes place in and next to residential areas, so access to homes, noise, vibrations, and dust are a challenge for construction,” Schram says. To address concerns, “the team re-evaluated when street closures could occur to allow demolition to happen earlier in the day or over a weekend to limit the amount of noise at night.”
The construction team also closely coordinated with the City of Council Bluffs in regard to street closures and detours and with three separate contractors working on three other projects directly adjacent to this one – including a Nebraska DOT project to the west.
“Careful coordination between all projects is needed to keep traffic moving safely throughout the area and not cause driver frustration from multiple, confusing detours,” Schram says.
The project team also has coordinated with mapping agencies – such as Waze, Google and Apple – to ensure the services have up to date roadway closures and openings.
“Allowing major interstate closures has meant that reconstruction can advance at a faster pace, reducing the anticipated construction duration from five and a half years to a little more than three years,” he adds.
In November 2021, the northbound I-29 mainline was closed through the project area and in March 2022, southbound I-29 was closed just north of 9th Avenue, with plans to fully close later this year. In addition, three of the four system ramp movements were closed in the project area. A combination of local and regional detours was developed to accommodate interstate traffic.
“The new frontage roads that parallel I-29 – as well as the realignment of West Broadway – were built first to provide a project area detour for most of the interstate traffic, allowing for major interstate system closures,” Schram explains.
Adaptive traffic signal technologies were used along frontage roads and West Broadway intersections. This technology adjusts the timing of the traffic lights as traffic patterns change to address congestion.
“This type of technology is rarely used within an active construction project,” Pohlmann says. “However, it has proven to keep traffic, which includes interstate traffic, moving efficiently and safely, even during heavy peak traffic periods.”
Traffic is scheduled to return to I-29, I-480 and the interchange ramps in 2023. This interchange project is anticipated to finish by summer 2024.
“When complete this project will change the landscape of this interchange and how drivers move through it,” Schram concludes. “The project already has provided local area access where there previously wasn’t.”
Photos courtesy of Iowa Department of Transportation