So forget 2005, the warning signs date back to 1990 (via the AP): Minn. bridge problems uncovered in 1990
Minnesota officials were warned as early as 1990 that the bridge that plummeted into the Mississippi River was “structurally deficient,” yet they relied on a strategy of patchwork fixes and stepped-up inspections.
“We thought we had done all we could,” state bridge engineer Dan Dorgan told reporters not far from the mangled remains of the span. “Obviously something went terribly wrong.”
Indeed.
It is not surprising that a patchwork approach was taken, given the expense needed to a replace a bridge of this size and span.
Here are some further details, which are not comforting:
In 1990, the federal government gave the I-35W bridge a rating of “structurally deficient,” citing significant corrosion in its bearings. That made it one of 77,000 bridges in that category nationwide, 1,160 in Minnesota alone.
The designation means some portions of the bridge needed to be scheduled for repair or replacement, and it was on a schedule for inspection every two years.
During the 1990s, later inspections found fatigue cracks and corrosion in the steel around the bridge’s joints. Those problems were repaired. Starting in 1993, the state said, the bridge was inspected annually instead of every other year.
Give them credit for taking the warnings seriously, but clearly (and tragically) not seriously enough.
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Interestingly enough, it seems that Minnesota is actually one of the states with the smallest amount of “structurally deficient” bridges in the country - certainly, my home state of Pennsylvania has thousands more bridges than Minnesota in that category. Maryland has a few bridges with this designation as well, which gives me pause.
This advantage didn’t stop this particularly structurally deficient bridge from collapsing, though. Very sad, and let’s hope that we figure out the best way to go about replacing our aging bridges. I have a bad feeling that this may happen more as the Interstate Highway system ages, and more and more of the bridges built to accommodate this huge expanse of roadway become old and rickety. (And as we keep driving more and more cars on these older and more rickety bridges.)
Comment by B. Minich — Thursday, August 2, 2024 @ 9:18 pm
Part of the problem is that spending money to repair a bridge will only cause traffic delays that will upset motorists, while spending the same amount of money on a brand new stadium will create excitement and attract votes.
This is a terribe tragedy. And it’s only a symptom of an older problem.
Comment by Max Lybbert — Friday, August 3, 2024 @ 11:29 pm
I can’t believe that there are 1,160 bridges in Minnesota which are about to fall down.
Perhaps part of the problem is the system of labeling the integrity of bridges. Is there a classification more serious than structurally deficient? If so, how many bridges are classified as such?
If there isn’t such a classification, perhaps there should be in order to prioritize the repair/rebuild schedule…
Comment by doug — Sunday, August 5, 2024 @ 12:38 am