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Second strut being installed on I-74 bridge, 10 arch segments remain

Second strut being installed on I-74 bridge, 10 arch segments remain

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Early surveys of the Illinois-side arches for the new Interstate 74 bridge show promise of hitting alignment targets.

Danielle Alvarez, project manager for the Iowa Department of Transportation, DOT, said preliminary surveys suggest the arch legs on the Illinois side of the Mississippi River are similar in alignment to the Iowa side arch legs that were joined last month.

Officials at the DOT were pleased last month, they said, to learn the nearly 300-foot-long arch legs that rise from foundations near the Bettendorf shoreline are within a half-inch in length of each other. Those results were determined as workers added the first permanent strut to the top arch segments on the Iowa side — lateral braces that will supply the arch system with support and rigidity.

The next real test will come after cable stays are back in place on the Illinois-side arches.

"We do not yet have final survey information," Alvarez said. "While multiple surveys will be performed, the one that determines the final position is the one performed after the next set of stays are installed."

The stays are collections of thick cables that are housed in piers on the river, then strung onto the arches and used to help guide them toward their proper meeting point above the Mississippi.

Officials with the DOT also have been satisfied by the recent pace by lead bridge contractor Lunda Construction in raising arch segments. In a recent period of about two weeks, two new arch rib segments were added to the Illinois side.

During the summer construction season, progress on arch erection slowed to less than one rib segment a month. The next segments cannot be added until the current work is completed on the Illinois side.

"Lunda will be installing the strut and next set of cable stays, and we anticipate installing both will take a few weeks, weather permitting," Alvarez said. "The next segments will be installed after both the strut and upper stays are installed.

"We have ten more arch rib segments and three struts to install to complete the Iowa-bound arch."

The westbound span of the $1.2 billion project is about a year behind schedule. The bridge deck (driving surface) cannot be placed until the arches are finished. But Lunda has gained considerable ground since late fall.

In November, DOT officials acknowledged a couple of disputes with the contractor, including whether the design of the bridge arches is "constructible" and at what cost. Lunda's contract is for $322 million — a bid that was $64 million under the state's estimates.

But Lunda has asked for more money. While some contract modifications have been granted by the DOT, only portions of the additional funding have been approved and paid.

Still to be determined is whether and to what extent Lunda may be assessed financial damages for failing to meet contract deadlines. The former director of the Iowa DOT said in November that negotiations with Lunda, "could lead to litigation."

Since then, however, the pace of progress has improved.

In addition to the four intermediate struts needed for both spans, they also will have a total of four keystone struts at the highest point of the arches.

To make up for the slight variation in the length of the arch legs, workers added a pre-fabricated fill plate to the ends of the arch ribs on the Iowa side. The final surveys will determine what size fill plate is needed for the first Illinois-side strut.
  
 
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