The first few months of the year have been especially productive for the builders of the new Interstate 74 bridge.
Each of the four legs of the all-important arch for the new Iowa-bound span are just one segment away from completion. In recent weeks, four arch segments have been added for a total of 24 out of the 28 needed.
Two keystone struts will be installed at the top of the arch after the final four segments are set, and the contractor then can move on to the remaining bridge deck. The arches have to be fully in place before the girders can be set and concrete poured for the driving surface between the arches.
"Our goal is to complete the arch in the spring," said Danielle Alvarez, project manager for the Iowa Department of Transportation. "We will continue progress on the bridge deck (including installation of the arch floor system) throughout the summer, and our goal is to complete the Iowa-bound bridge in the second half of 2020."
Previous payment and design disputes between the Iowa DOT and bridge contractor Lunda Construction now appear to be resolved.
"We are working closely with Lunda on this timeline, and recent progress on the arch shows promise for meeting our goal," Alvarez said.
As the remaining arch segments — also called ribs — are staged on a barge in the construction zone on the Mississippi River, the keystone struts are being simultaneously assembled, she said. Two other lateral struts were set in the arches in recent months, and the process showed the complex arch ribs are correctly aligned.
"Lunda’s ironworkers and crane operators have been doing a great job installing each arch segment, and we’ve been pleased with the speed of progress this year," Alvarez said.
The new pace would suggest a hopeful outlook for the timeline for the Illinois-bound span and arch, except that the two spans are not identical.
"We’ve learned a lot from our experiences on the westbound arch, but it’s important to keep in mind that the eastbound arch is actually more complex, primarily due to the cantilevered multi-use path," Alvarez said, referring to the bike/pedestrian lane on the downstream side of the Illinois-bound span. "The eastbound arch will support the added weight of the multi-use path, so special considerations must be made.
"We already have eight pieces of the eastbound arch on site. Fabrication of the other segments are nearly complete, and (they) will be delivered later this year."
Bridge construction is not immune to the COVID-19 pandemic that has had an impact on so many other aspects of life. However, the spread of the virus is not shutting down operations.
"Right now, we’re working to continue on with critical construction operations while following guidelines relating to the pandemic," Alvarez said. "We are limiting size of working groups (and) handling communications via phone."
The westbound span of the new I-74 currently is about a year behind the original construction schedule. The setbacks are attributable largely to harsh weather and flooding, though the contractor/DOT dispute also contributed.
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