NORTH LIBERTY — Interstate 380 could get a new bridge protected from flooding and another lane in each direction between Forevergreen Road and Highway 30 under a proposal from the Iowa Department of Transportation.
Under the Iowa DOT’s plans, shown to the public Wednesday evening. the additional lane in each direction would go on the outside of the current two lanes, allowing the agency to fill in the median with a fourth lane if need be.
However, the Iowa River Bridge and Highway 965 crossing would get lanes on the inside so that widening could be done without significantly impacting the Coralville Lake or Hawkeye Wildlife Management Area, said Cathy Cutler, a transportation planner with the Iowa DOT.
Additionally, the Iowa River Bridge would be raised to protect it from future flooding.
The entire project is estimated at $203 million.
“I think the Corridor is ready for it,” Cutler said.
If approved, work on the project would not begin until construction is complete on revamping the Interstate 80/380 interchange — a major undertaking by itself that will affect traffic patterns for years. As part of that project, I-380 already is planned to be widened in both directions from I-80 to Forevergreen.
Continuing the interstate widening north of Forevergreen would require making improvements at three interchanges — Penn Street in North Liberty, 120th Street at Swisher and Shueyville and Wright Brothers Boulevard, a key route to The Eastern Iowa Airport. None of the bridges over I-380 at those interchanges are long enough today to accommodate widening to a total of six lanes.
Cutler said the Iowa DOT is proposing new interchanges for Wright Brothers and Penn that are known as “diverging diamond” interchanges. Those interchanges would have a similar footprint to what currently exists, but would be better-suited to handle traffic. The 120th Street interchange would be rebuilt with the current diamond configuration.
The proposed changes would help address safety and reliability on that stretch of I-380, Cutler said. Nearly 7,000 commuters use that route regularly, Cutler said.
“We see a lot of crashes out there, especially if something is happening on the side of the road,” she said. “That can really clog things up ... We want to make sure it’s safe for people and give them more lanes to use.”
Cutler said in studying I-380, the Iowa DOT considered alternatives including active traffic management — implementing variable speed limits, hard-should
er running and ramp metering to regulate traffic flow — as well as alternate travel modes such as buses or using the CRANDIC line for a trolley or passenger rail. Ultimately, planners found that adding lanes in each direction was the best way to go.
According to the Iowa DOT, annual average daily traffic has climbed from 42,000 vehicles in 2009 to more than 50,000 now. Cutler said the daily average is expected to climb to 90,000 by 2040.
On Wednesday evening, the Iowa DOT hosted an open house in North Liberty to gather public comments on the proposal. Sean Smith, 41, of Cedar Rapids, is among those in favor of the lane additions.
“I’m definitely glad it’s moving forward,” said Smith, who primarily travels I-380 on the weekends, but occasionally for work on weekdays. He’s employed by Alliant Energy. “I think it’s definitely been needed for several years.”
The project first would have to be approved by senior agency management and the Iowa DOT Commission. Funding could be set aside as early as fiscal 2021, but construction would not begin until after the I-80/380 interchange work is done in 2023, Cutler said.
That would give the agency time to complete design work and right of way acquisition, which would take two to three years, Cutler said.
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The widening project would not impact the timelines for other road projects in the region, such as those scheduled for Tower Terrace Road and Boyson Road.
Once construction begins, it would be done in phases. Cutler said rebuilding an interchange takes about two years; and a few miles of lane widening could be done at that time, as well.
“It could easily be six years of total construction or more,” she said. “We could do an interchange and 4 miles in two years.”
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