Even as the lead contractor on the new Interstate 74 bridge says the steel arches are "not constructible," work continues.
Lunda Construction has a $322 million contract with the Iowa DOT to build the bridge. Other contractors are responsible for the new approaches, reconfigured sections of interstate and other aspects of the $1.2 billion project.
Over the summer construction season, Lunda made considerably less progress on the arches than was expected. Those delays now are pushing the timeline for finishing the Iowa-bound span into late next year. It originally was to be finished this season.
In addition to the complicated nature of the arch raising — attributable to its precise geometry — is a dispute between Lunda and the DOT over the design. The basket-handle design is not merely an aesthetic feature; it supports the load of the bridge itself.
In a statement by the company last week, Lunda acknowledged it "has encountered issues with the design; specifically the geometry of the arch and tolerances utilized in the design."
Tolerances are the allowable variations from the arch plans, and the DOT has taken the position those specifications are solid.
Danielle Alvarez, the Iowa DOT's project manager for the I-74, said Friday the state's position has not changed.
"We are confident in the design and committed to building a safe, sound structure," she said.
However, Lunda's position also has not changed, she said.
The new spans, with four lanes in each direction and a pedestrian/bike lane, were designed by teams from Pennsylvania-based Modjeski and Masters and Chicago-based Alfred Benesch & Co. Modjeski and Masters designed the current I-74 bridge, and the firm's founder, Ralph Modjeski, designed the 123-year-old Government Bridge at the Rock Island Arsenal.
Contacted last week for comment on constructibility disputes surrounding their design, both companies declined to answer questions or supply statements. A senior vice president at Benesch said the company was asked to direct all questions to the state. While the DOT's Bridges and Structures Bureau last week clarified for the two design firms that they were not prohibited from publicly discussing their roles in the project, both companies again declined to do so.
Meanwhile, four new sections of arch were added in recent weeks — one on each leg. Additional segments now are not expected until early December, Alvarez said, because many steps must be taken on each segment before more are added.
"... about 1,300 bolts are installed in each segment to secure it to the arch, and the bolts are then tensioned in a specific sequence," she said. "With the latest segments, we must install temporary struts and lateral bracing.
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"After each segment is installed, surveying of the arch is performed, and we analyze the location of the arch ribs to determine next steps for installing the next arch segment. In addition, we prepare the next arch segment by placing it on a barge, rigging it, and performing other tasks to get it ready for installation."
As the arch segments on either side of the river get closer to meeting in the middle, surveying methods will determine their trajectory — that is, whether they are on course to converge.
Until more progress reveals whether Lunda or the Iowa DOT is correct about the constructibility of the new bridge, Alvarez said the work is under constant review, including full-time on-site inspection staff that monitors every aspect of the build.
"Inspectors check everything, including testing concrete strength, fabrication and installation of the arch segments, tensioning of the bolts, quality of the welding, and review surveying results," she said. "We have established procedures for monitoring construction to ensure quality of the structure and that each element meets design requirements."
While the contractor and the state disagree on the design, they also remain in negotiations over money.
The parties agreed on some contract modifications in the spring that could have given Lunda about $16 million more in exchange for hiring more workers and performing nighttime work to make up for lost time on the westbound span that resulted from spring flooding.
In those contracts, Lunda estimated the Iowa-bound arches and floor system would be finished Nov. 4. On that date, however, the arches were not halfway finished. Some, including former and current Lunda workers, some iron workers and engineers on other parts of the project, said they suspected Lunda was delaying construction on purpose in an effort to pressure the DOT into paying them more.
Of nearly $16 million in possible payments for catch-up work, however, the DOT has paid only $3.9 million, Alvarez said.
By the end of May, she said, "it was apparent that second-shift work was not geared toward the completion of the westbound bridge. We discontinued any further payments for second-shift work for this reason."
As of last week, Alvarez said, negotiations were ongoing.
Five contractors bid on the I-74 bridge, and Lunda's $322 million came in lowest. The highest bidder, Johnson Brothers, was nearly $100 million higher than Lunda at $416 million. Lunda's bid was about $35 million lower than the second-lowest bid.