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Construction Corner: New generation of sensors installed on Michigan bridge

Korky Koroluk
Construction Corner: New generation of sensors installed on Michigan bridge
Korky Koroluk

A new generation of infrastructure monitoring got out of the laboratory and into the real world a couple of weeks ago when a wireless system using specially designed sensors combined with cloud computing and storage was installed on the Mackinac Bridge in northern Michigan.

The sensors were developed by engineers at Washington University in St. Louis, Mo. The cloud computing system was developed to accommodate the next-generation of sensors.

The work was supported by a grant from the U.S. National Science Foundation. Its goal, over the four-year life of the grant, is to create smart civil infrastructure that can monitor itself, enabling it to predict any failures in case of extreme events like earthquakes or floods and also to prioritize areas for emergency response.

Cloud computing has been around for a couple of decades and many people use it without realizing it. If you use Dropbox or Google Drive your documents are being stored in the cloud. Many computer backup systems also store your backups in the cloud.

The new sensors are able to generate power from tiny movements, such as vibration or strain. That’s because they contain piezoelectric elements. Piezoelectricity is the appearance of a voltage across the sides of a crystal when it’s subjected to mechanical stress.

So if you design a sensor that contains a crystal of some sort, then stress it, it will generate a small, but measurable current — enough to eliminate the need for a traditional battery. In fact, the sensors used on the Mackinac Bridge installation can produce enough electricity to power a wireless network used for transmitting data to a scanner mounted on a truck. The scanner sends the data to the cloud for analysis and storage.

The research team is led by Shantanu Chakrabartty, a professor of electrical and systems engineering at Washington University. But collaborators in work done under the grant are from Michigan State University and the University of Nevada-Reno. A key characteristic of the sensors is that they can be produced at such a low cost that large numbers can be embedded in the concrete in roads, bridges and buildings.

The Mackinac Bridge, which links Michigan’s upper and lower peninsulas, was chosen for a first installation of the sensors because, as the largest suspension bridge in the western hemisphere, it provides a high-visibility test bed.

It’s an important step toward smart civil infrastructure and not just in the United States. If the system works out on the Mackinac Bridge and is brought to market, Canadian owners of civil infrastructure will be interested. There has been a lot of hand-wringing about the state of North American infrastructure. Canada is somewhat better off than the United States is, but there is still a gap between the infrastructure we need and the infrastructure that we have.

With most levels of governments operating on tight budgets, finding the money to build new infrastructure is difficult. It’s better to ensure that we get the maximum life out of what we already have, which means spending more on maintenance.

Chakrabartty says the sensors "are going to continuously monitor the health of the structure, and if something goes wrong, then they’re going to report that to the cloud.

"You never lose the data. So if something happens, you can go back and see that a certain part of the structure experienced abnormal levels of strain."

Staff can then mount an emergency response or schedule maintenance.

Bob Sweeney, of the Mackinac Bridge Authority, says he’s excited about having the prototype system installed on the bridge. He says the system will complement the bridge’s normal maintenance activities.

Xuan Silvia Zhang, a member of Chakrabartty’s team, says the technology they have developed "we can deploy all over.

"We are truly making an impact to make people’s lives safer."

Korky Koroluk is an Ottawa-based freelance writer. Send comments to

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