As you travel each day, your cell phone could help you determine the health of bridges.
The standard components of smartphones are GPS sensors and accelerometers. These sensors collect information. Can show how bridges vibrate and flex.Researchers report November 3rd on vehicles moving across the country, Communications Engineering.
An app that measures the distance between two points could alert engineers to the need for repairs and keep travelers safe. The tools can also be used to help detect or prevent damage. Katastrophic FailuresLike the horrific collapse of a footbridge in Gujarat, western India on October 30th, or the bridge that gave way in Pittsburgh in JanuarySN: 11/16/07).
“This is really applicable to any type of bridge,” says civil engineer Thomas Matarazzo of the U.S. Military Academy at West Point in New York. All you need, he says, is a way to get a smartphone on there — whether by car, in the A pocket for a pedestrian or mounted to a scooter — and some way of monitoring the device (SN: 11/10/17).
Matarazzo claims that bridge failures are often due to uncertainty about structural properties. “The only way to reduce those uncertainties is to monitor more frequently.” Crowdsourcing data from cell phones may be the best, and possibly only, way to get lots of data on bridges around the globe.
In the United States alone, there are more than 600,000. Matarazzo states that dedicated sensors to check for structural problems can be expensive so bridges are usually inspected by the eye every other year.
Keeping up on bridge conditions using simple cell phone apps could make maintenance more efficient than is possible with human inspectors alone — and much cheaper than is possible with specialized sensors. The resulting improvement in care would extend the lifetimes of older bridges by a few years, Matarazzo and his colleagues estimate, but newer bridges could last nearly 15 years longer than if they weren’t monitored in this way before needing to be rebuilt or replaced.
Matarazzo drove his car over the Golden Gate Bridge in San Francisco, California 102 times using his cell phone. This was to see how cell phones monitor bridges. His research team also collected data about Uber drivers on 72 trips across the suspension bridge. Researchers arranged for Uber drivers to log data over 280 trips over the concrete bridge, which is nearly 30 meters long, in Ciampino (Italy) to check their approach.
Both bridges had cell phone sensors that detected vibrations that were less than 1% of the measurements that bridge-specific instruments could provide.
Matarazzo states that a single pass made with a mobile phone can gather as much information as a hundred stationary sensors about a bridge. That’s because phones can take data continuously as they cross, rather than offering data from specific locations along a bridge.
The researchers could collect more data if they can get transportation companies, government vehicle drivers, and the general public to cooperate. This would allow for extremely precise measurements. Information could be collected almost for free, since most smartphones already have GPS and accelerometers.
Huili Wang, a Chinese civil engineer who wasn’t involved in the study, believes that cell phones could be used to monitor bridges without sensors. He is skeptical about how accurate smartphones can be. Still, “it is a better approach for a rough estimate without [adding] more sensors,” he says.
Crowdsourced data probably won’t entirely replace dedicated sensors for monitoring bridges, Matarazzo agrees. He says cell phones are superior in some ways. “The advantage is in the convenience and the scale…. It’s a mobile-sensing system that’s already in place.”
Bridges are a key component of transportation infrastructure. It’s crucial to look at changes in them that can occur in days and weeks, Matarazzo says, rather than checking on bridges every few years. “This technology enables us to do that.”
