Creators of an embedded sensor system claim engineers will be able to identify potential structural problems with roads before they reach the surface. ©Thinkstock
LANSING — If Michigan ever gets around to fixing its crumbling roads, engineers might be well-served to consider a new ingredient in the road-making mix.
It’s a sensor developed by Michigan State University, and it could have a big impact on road budgets and repairs nationwide.
The sensor records traffic data and measures impacts and damage to roads. It communicates that information to engineers who can use the data to fix roads before they become seriously damaged — making maintenance significantly easier and cheaper.
“If you’re trying to detect something in the roads, you have to do it at the bottom of the road — you cannot do it only at the surface because once the damage has reached the surface, it’s kind of too late,” said Nizar Lajnef, the MSU assistant professor of civil and environmental engineering who oversees the project. “You need to detect the problem early, before it turns up on the surface.”
The sensors “wake up” whenever a vehicle drives over them and record road stress and damage. When engineers check the sensors wirelessly, they can better understand which parts of the road may need internal repairs, wear faster and need more attention.
The sensors are entirely self-sustainable — powering themselves from the vibrations of the same traffic they record. It’s not enough to power traffic lights or other devices, but it’s enough to keep the sensors operating.
The pressure and vibrations created by vehicles serve a dual purpose — generating power and providing valuable data for proactive repairs. That’s important because the sensors can’t be removed for battery changes.
“You just mix it with the concrete, mix it with the asphalt, and then you just lay it down on the road and it starts working,” Lajnef said.
The sensors should power themselves for the life of the road.
“The sensor needs less than a microwatt of power,” said Shantanu Chakrabartty, a professor of computer science and engineering at Washington University in St. Louis, Missouri.
“To give an idea, one microwatt is about 10 times less than the energy it takes to power your wristwatch,” said Chakrabartty, who worked with MSU in developing the sensor technology.
Chakrabartty said the technology also has implications for things like body implants, including knee replacements, monitoring implants after surgery and tracking bone growth after a break.
The sensors also could be used to measure and improve the efficiency of wind turbines, he said.
The project began in 2006 and moved to commercial development in 2010, Chakrabartty said. The U.S. Department of Transportation and the Federal Highway Administration have supported the project with grants totaling $2 million, he said.
The sensors are being tested at the Turner Fairbanks Research Lab in Washington, D.C., where researchers have access to different vehicle weights and road types and can better control the evaluations.
They could be tested in small sections of actual roads in Virginia and Michigan within the next year, Chakrabartty said. A commercial release is still a few years away.
“Within a couple of years we will have a better idea of the reliability and also the performance of the sensors under real conditions,” he said. “Right now, we have tested everything within testing facilities, where we simulate the road and we simulate damage. But, in a couple of years, we will have better results.”
The developers said they hope that the sensors will become a basic part of highways.
“Our goal right now is to reduce the cost to about a dollar per sensor,” Chakrabartty said. “And then, based on that, we have to plan what other features we would need on top of that.”
Those features would mainly be tweaks to make the sensors easier to use, he said.
How many are needed per mile depends on the road; however, the number will likely be in the hundreds for the average 1-mile stretch.
In the long run it will still be a cheaper and more effective solution than constant road repairs, the developers said, and sensors only will need to be replaced when roads are replaced, which can be more than a decade.
“There’s a lot of customer education that needs to go into it,” Chakrabartty said. That includes learning which highway departments want the data.
If the researchers can demonstrate to transportation departments that the technology is effective, improves repairs and reduces costs, Chakrabartty said he’s confident they will use it.
“The fact that (the sensors) generate their own power, we think is a good selling point,” Lajnef said.
Chakrabartty agreed: “Sustainability and environmental impact is one of the key aspects of this technology. Effectively, it decreases the carbon footprint from that point of view because you don’t take on the maintenance blindly — only when it’s needed.”