When the Francis Scott Key Bridge collapsed in Maryland last month, footage of its swift and lethal fall prompted concern about the safety of bridges across the country. For many people in Michigan, the Mackinac Bridge came to mind.
Bridge safety has been on Louis Mleczko’s mind long before this collapse. As the former transportation beat reporter for the Detroit News, Mleczko published a story in 1989 about the vulnerability of the supports beneath the Mackinac Bridge. Marking clear parallels between these two bridges, he cited a lack of protection from boat strikes as a key deficiency of the bridge.
Leading up to publishing this story, Mleczko spent about a week covering the death of Leslie Pluhar, who lost control of her vehicle on the Mackinac Bridge and fell to her death in the Straits of Mackinac. Through his reporting, Mleczko developed a network of engineers he could rely on to inform his work on bridge safety. However, following this accident and Mleczko’s subsequent reporting, there were no changes made to the Mackinac Bridge.
“MDOT and bridge authority officials have been resistant to changing anything at the bridge,” Mleczko said. “To this day, that antiquated railing curb system is still the feature of the Mackinac Bridge.”
Mleczko pointed out that the Mackinac Bridge was built without protective pilings, which are separate structures adjacent to the vertical piers that support a bridge. He said that this is a common structural issue with bridges around the world, citing a report from the New York Times that found there were 35 major bridge collapses worldwide between 1960 and 2015 as a result of ship or barge collisions.
While many people see the sturdy suspension towers of the Mackinac Bridge and assume the bridge to be solidly constructed and protected, Mleczko said there are 33 vertical piers that are “totally exposed” to a ship losing power or control.
“As engineers told me, a ship going off course, for whatever reason, could slice through that four lane bridge like a hot knife through butter,” Mleczko said.
The technology to protect these piers was available at the time of the bridge’s construction, and was implemented in other bridges such as the Golden Gate Bridge. However, Mleczko said that cost was a concern throughout the construction process.
“When the Mackinac Bridge was being built, starting in 1950, the Michigan legislature finally, reluctantly agreed to issue $100 million in state bonds to build the bridge, which was an astronomical sum of money back in the day,” Mleczko said. “Unfortunately, they are under a lot of pressure to hold down the cost as much as possible.”
While David Steinman, the designer of the Mackinac Bridge, took many precautions to ensure weight limits would be considered, protective pilings were not implemented in the bridge.
Today, there are efforts around the country to make bridges more comprehensively protected. Mleczko mentioned that transportation officials in Delaware and Pennsylvania agreed to spend $93 million to install protective pilings for the Delaware Memorial Bridge over the Delaware River, a project that is currently underway.
Dr. Venkatesh Kodur, a professor of civil and environmental engineering at Michigan State University, spoke to how these protections are added to existing bridges.
“[Bumpers] can be implemented in the current bridges we have, but it requires a little bit of effort,” Kodur said. “For the existing bridges, it can be done, but it requires some planning, a little bit more cost than what it would have been when it was originally built.”
Kodur recounted his shock upon hearing about the collapse of the Francis Scott Key Bridge. He pointed out that, even with technological advancements, “nothing is 100% foolproof.” He also mentioned the manpower and materials required to implement today’s construction technologies into existing bridges.
“It's not like a bridge on I-96 where you go [to] it at the level ground and you implement these things — it's a little bit easier — but, in water, it's a big challenge even today,” Kodur said.
While major bridge collapses create an uptick in concern over bridge safety, Kodur pointed out that bridges are inspected every five years and emphasized that they are built “to the highest standards.”
To learn more about how our bridges are constructed and protected, listen to the Stateside podcast.
GUESTS ON THIS EPISODE:
- Venkatesh Kodur, professor of civil and environmental engineering, Michigan State University
- Louis Mleczko, former transportation beat reporter for the Detroit News
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