The Leo Frigo Bridge crossing the Fox River as seen from Green Bay Metro Boat Launch. (PHOTO/WTAQ News)
GREEN BAY, WI (WTAQ-WLUK) — Nearly one year ago, the Francis Scott Key Bridge in Baltimore collapsed after a ship struck it, killing six construction workers.
As part of its ongoing investigation into that tragedy, the National Transportation Safety Board also looked at other bridges across the U.S. Only one bridge in Wisconsin caught the NTSB’s eye.
They are recommending the assessment of the Leo Frigo Memorial Bridge in Green Bay for safety risks.
In its report released Thursday, the NTSB found there are 30 owners of 68 bridges over navigable waterways frequented by ocean-going vessels that are likely unaware of their bridges’ risk of collapse if it were struck.
“Today’s report does not suggest that the 68 bridges are certain to collapse,” the NTSB said. “The NTSB is recommending that these 30 bridge owners evaluate whether the bridges are above the [American Association of State Highway and Transportation Officials] acceptable level of risk. The NTSB recommended that bridge owners develop and implement a comprehensive risk reduction plan if the calculations indicate a bridge has a risk level above the AASHTO threshold.”
Wisconsin Department of Transportation Bureau of Structures Director Josh Diestche says, “It’s on there because they did a high-level look at some of the data — really just looking at bridges that can possibly have larger ship traffic running underneath it, and were built before some of the more recent guidance on how to protect from vessels.”
With a clearance of roughly 120 feet, Green Bay’s tallest bridge was listed as critical/essential if a vessel were to crash into it. Diestche said this report doesn’t signify any new risks.
That is not a measure of the bridge itself of how risky or not it might be. It is simply labeled that way because it carries I-43. Because it carries interstate traffic, it gets put into that category.
The Leo Frigo Bridge was built in 1981, only a few years after the Francis Scott Key Bridge.
Diestche said, “The ship that impacted that was much much larger that what is even capable of entering the port of Green Bay, so both size wise and the amount of cargo they are able to carry. We just don’t see ships that size that are able to access the port, so that limits the risk in itself.”
Back in 2013, portions of the Leo Frigo started to sag, which led to the bridge being closed for over three months. Diestche says they remain confident with the protections in place.
“There are four piers which support the bridge that are in the water. Two of them are in very shallow water where no large ship would be able to reach. The two that are in water get a bit deeper, but again, there are some protections out there,” says Diestche. “There are what are called dolphins — big concrete cylinders, basically, that are in place to protect the bridge. The channel itself offers some protection to it — it is deepest in the middle and gets much shallower toward the piers.”
According to the WisDOT, all bridges in Wisconsin are inspected at least once every two years.
In the NTSB’s report, it listed the Mackinac Bridge in the U.P. as Critical/Essential.
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