Smartphones might function as already-installed mobile integrity sensors.
Simply by being in your pocket as you go about your regular trips, your cell phone might provide information about the condition of bridges.
Researchers report November 3 in Communications Engineering that accelerometers and GPS sensors, which are commonplace in cellphones, collect data that can demonstrate how bridges flex and vibrate as vehicles cross them.
Travelers could be kept safe by using apps that collect the measurements to notify engineers when a bridge needs to be repaired. Additionally, the instruments could foresee catastrophic failures or contribute to their prevention, such as the fatal footbridge collapse in the western Indian state of Gujarat on October 30 or the collapsed bridge span in Pittsburgh in January (SN: 11/16/07).
According to American civil engineer Thomas Matarazzo, “This is truly relevant to any form of bridge.” West Point Military Academy in New York. All you need, according to him, is a way to get a smartphone onto the device—whether by car, in a pedestrian’s pocket, or fastened to a scooter—and a method of checking it (SN: 11/10/17).
According to Matarazzo, structural property uncertainties are frequently the cause of bridge failures. Crowdsourcing data from cell phones may be the greatest, and possibly the only, method to obtain a lot of data about bridges around the world. “The only way to lessen those uncertainties is to monitor more frequently.”
There are more than 600,000 bridges in just the United States. According to Matarazzo, dedicated sensors that check for structural issues are expensive, so the majority of bridges are visually inspected, often once every two years.
Simple mobile apps could make monitoring bridge conditions more efficient than it is with human inspectors alone, and far less expensive than it is with specialised sensors. Newer bridges might last nearly 15 years longer than if they weren’t monitored in this way before needing to be rebuilt or replaced, according to Matarazzo and his colleagues, who estimate that the consequent improvement in care would extend the lifetimes of older bridges by a few years.
Matarazzo crossed the Golden Gate Bridge in San Francisco 102 times while using cell phones to see how successfully they could monitor bridges. During 72 journeys across the suspension bridge, he and his research team also gathered information from Uber drivers. The researchers arranged for vehicles to record data during 280 crossings over a nearly 30-meter-long concrete bridge in Ciampino, Italy, to test the method on bridges more representative of the overpasses that are frequently found on motorways.
Cell phone sensors on both bridges were able to monitor vibrations within a few percent of what specialised instruments mounted to the bridges could measure.
According to Matarazzo, a single pass with a cell phone can collect as much data about a bridge as a hundred or more stationary sensors. This is so that phones can collect data continuously rather than only at specified points along a bridge.
If the researchers are successful in enlisting the assistance of transportation providers, drivers of public transportation, or members of the general public, they may be able to gather far more data and provide measures that are incredibly accurate. Since most smartphones already have GPS and accelerometers, data collection may be done essentially for nothing.
According to Huili Wang, a civil engineer from the Dalian University of Technology in China who was not involved with the study, cell phones could help monitor bridges that don’t have installed sensors. However, he has reservations about the level of accuracy that smartphones can deliver. Nevertheless, he claims that “it is a superior way for a rough approximation without [adding] more sensors.”
Matarazzo agrees that crowdsourced data most likely won’t completely replace specialised sensors for monitoring bridges. However, he claims that there are several aspects in which cell phones are incomparable. “The convenience and size are the advantages…. There is already a mobile sensor system in place.
Bridges are important components of the transportation system. Instead of inspecting bridges every few years, Matarazzo argues that it’s important to pay attention to changes in them that can happen in days or weeks. “We can do that thanks to this technology.”