As long as it is in your pocket, your phone can reveal the health of bridges on your daily trips.
Information collected by accelerometers and GPS sensors that are standard components of smartphones Can show how bridges bend and vibrate When the vehicle crossed, the researchers reported on Nov. 3 Communication Engineering.
Apps that collect measurements could keep travelers safe by alerting engineers that bridges need repairs. These tools can also warn or help prevent, catastrophic failure Like the tragic pedestrian bridge collapse in the western Indian state of Gujarat on October 30, or the collapse of bridge spans in Pittsburgh in January (SN: November 16, 2007).
“This really applies to any type of bridge,” said Thomas Matarazzo, a civil engineer at West Point, New York.All you need, he says, is a way to get your smartphone in there — whether driving or in pedestrian pocket or mounted on a scooter – and some way of monitoring the device (SN: November 10, 2017).
Bridge failures often boil down to uncertainty in structural properties, Matarazzo said. “The only way to reduce these uncertainties is to monitor more frequently.” Crowdsourced data from cellphones may be the best, or only way, to access the vast amounts of data on bridges around the world.
There are more than 600,000 bridges in the United States alone. Dedicated sensors to check for structural problems are expensive, so most bridges are inspected with the naked eye, usually every other year, Matarazzo said.
Using a simple phone app to keep up with bridge conditions can make maintenance more efficient than using human inspectors alone, and much less expensive than using dedicated sensors. Matarazzo and his colleagues estimate that the resulting improvements in care will extend the useful life of older bridges by a few years, but new bridges could be nearly as long as if they were not monitored in this way until they need to be rebuilt or replaced. 15 years.
To test the phone’s ability to monitor bridges, Matarazzo drove 102 times on San Francisco’s Golden Gate Bridge with his phone in his car. He and his research team also collected data on Uber drivers on 72 trips on the suspension bridge. To examine the approach to bridges that are more typical of overpasses commonly found on roads, the researchers had drivers record data from 280 passes on a nearly 30-meter-long concrete bridge in Ciampino, Italy.
For both bridges, the vibrations in the structure detected by the cell phone sensors differed by a few percent from the measurements that specialized instruments attached to the bridges could provide.
A phone can gather as much information about a bridge in a single pass as a hundred or more stationary sensors, Matarazzo said. That’s because the phones can take data continuously as they pass, rather than providing data from specific locations along the bridge.
If the researchers manage to get transportation companies, government vehicle operators or the public to collaborate, the team can gather more information, allowing for extremely precise measurements. Since most cell phones already have accelerometers and GPS, the information is basically collected for free.
Phones could help monitor bridges without sensors, said Wang Huili, a civil engineer at China’s Dalian University of Technology who was not involved in the research. But he is skeptical of the ultimate accuracy smartphones can provide.Nonetheless, “for a rough estimate, this is a better approach without [adding] More sensors,” he said.
Crowdsourced data may not completely replace dedicated sensors monitoring bridges, Matarazzo agrees. But he said the phone was unrivaled in some ways. “The advantage is convenience and scale…it’s a mobile sensing system that’s already in place.”
Bridges are an important part of transportation infrastructure. Instead of inspecting bridges every few years, it’s crucial to watch how they can change over days and weeks, Matarazzo said. “This technology allows us to do just that.”