MINNEAPOLIS (WCCO) — Ten years after the catastrophic collapse of the I-35W bridge in Minneapolis, Minnesota has completely overhauled how it builds and inspects bridges. Many old bridges are gone, and many new ones are in their place.
The shock of that summer night evolved into an all-hands-on-deck moment for Minnesota — we learned about gusset plates, sufficiency ratings and load capacities. Then-Governor Tim Pawlenty ordered emergency inspections of every bridge in the state and the legislature passed a 10-year program to repair or replace crumbling bridges.
Minnesota’s top bridge engineer says he and his colleagues felt the pressure to find out what exactly happened.
“We really weren’t doing anything wrong, but there are always ways to do things different and improve,” said Kevin Western, Minnesota’s top State Bridge Engineer. “Nationally there was a spotlight put on bridges when the collapse happened. As a bridge engineer, we were concerned. Are there other things that we are missing?”
Western and his colleagues reviewed inspection reports, bridge designs and service records. They brought a sweeping bridge repair plan to the legislature to address what turned out to be an aging — and sometimes deteriorating — infrastructure.
“We’ve come a long way,” said Western.
In 2008, Minnesota classified 172 bridges as “fracture critical” or “structurally deficient.”
- 119 bridges are now substantially complete, including 100 new bridges.
- 4 new bridges will be finished by the end of 2017.
- 14 are scheduled for repair or replacement by 2018.
In addition to humans, the state now uses drones to get up and under bridges for inspection. The new technology allows infrared inspections from above, as well as 3-D imaging.
Every critical bridge gets an in-depth inspection one year, and a safety inspection the next.
“Instead of having an inspection of the bridge, we actually inspect each element of the bridge,” said Western. “Looking at it and describing it’s condition. So now its really easy for us to look at a bridge and understand how the bridge is doing. How’s it’s health?”
Western says the 10-year program to repair and replace deficient bridges made Minnesota a state with some of the safest bridges in the United States, and that another bridge collapse is highly unlikely.
“In Minnesota, I’m confident that we have put all of the measure in place so that it will not happen here,” he said.
That 10-year program will end in 2018, and state officials say not all Minnesota bridges have yet received the repairs they need.