I-35W bridge is aging, seven years after collapse

  • Article by: PAT DOYLE , Star Tribune
  • Updated: July 27, 2014 - 8:08 AM

In the six years since the official I-35W Bridge opening in 2008, left, the bridge has deteriorated from “excellent” to “very good.”

Photo: David Joles• djoles@star tribune.com,

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Cracks emerged in concrete girders. A drainage hole on the bridge deck plugged up. Rust showed above piers.

Seven years after the collapse of its predecessor, the new Interstate 35W bridge has been showing its age.

It cuts a handsome profile across the Mississippi River in Minneapolis, but annual state bridge inspection reports describe wear and tear that dropped its rating from “excellent” when it opened in 2008 to “very good” within two years.

While most of the changes are minor, a bridge engineer called one problem “rather major” — a leaky anti-icing system on the bridge deck. Repairs to the system were eventually made under warranty, but not before years of finger-pointing between the state and the lead contractor. Taxpayers also covered some costs.

“Contractors are always very reluctant to give anything,” said Tom Styrbicki, bridge construction and maintenance engineer for the Minnesota Department of Transportation (MnDOT). “They always try to drag MnDOT into it: ‘We did it per your specifications. If it leaks, it leaks.’ ”

“We held our ground on this one,” Styrbicki said. “And said, ‘Hey, we bought a bridge for a significant amount of money and … we want the systems to work.’ ”

A MnDOT engineer overseeing the warranty recalled a tussle. “They were resistant,” David Herzog said. “It took a long time and many phone calls and discussions to get the work done that needed to be done.”

Still, MnDOT wound up paying for other repairs to the anti-icing system that it conceded weren’t covered under warranty.

The lead contractor, Flatiron Construction of Colorado, declined to comment.

Urgency to build

There was urgency to replace the old 35W bridge after it fell into the river on Aug. 1, 2007, killing 13 people and injuring 145. Federal regulators blamed the disaster on improperly designed gusset plates for steel beams that fell when the bridge was heavily loaded with construction equipment. They also cited inadequate attention to the plates by state and federal officials during inspections.

From the beginning, the price tag for the new bridge was controversial.

Flatiron won the job with a bid of $234 million — higher than proposals from competitors who vowed to complete the project sooner. It then got another $25 million in bonuses from the state for finishing the work ahead of the company’s scheduled completion date.

At the time, MnDOT officials defended Flatiron’s proposal as far superior to the other bids when design, aesthetics and other factors besides price and schedule were considered.

Inspectors’ notes

A year after the bridge opened, MnDOT inspectors rated the deck, superstructure and substructure of the northbound span in “excellent condition” and the southbound span as “very good,” noting cracking on the deck in a couple of places. They dropped the rating of the northbound span to “very good” in 2010 after discovering cracking on two concrete box girders and a concrete railing, shrunken sealant and small areas of rust stains above the piers.

MnDOT described those changes as common in a new bridge.

“Excellent basically means brand new, out of the box, and the first year you get traffic on it, get it through a winter, it starts to show those little bits of deterioration,” Styrbicki said. Cracks were repaired and other flaws monitored.

More deterioration was noted in inspection reports from 2011 through 2013. The 2011 report said deck joints and seals “do not appear to be leaking, but … should be closely monitored during inspection.”

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