Smartphones can reveal whether bridges are about to fall down

Alex Wilkins is a writer.

It is possible to add more than a decade to the usable lifetimes of bridges by using data from phones.

It can take a long time for most bridges to be assessed. It would be costly to put the mounted sensors on all the bridges.

A group of people at the United States Military Academy at West Point, New York, have developed a system that uses movement data from phones to measure frequencies. To be able to collect the data that we need at scale, we don't have to buy any additional or special sensors.

The researchers collected data from phones while they were on the bridge. Any tiny movements the phone makes can be revealed from the data they use.

In the first part of the study, the researchers drove over the Golden Gate Bridge in San Francisco over and over again.

In the second, they took data from the drivers who completed 72 trips over the Golden Gate Bridge. The Ciampino bridge in Italy is more representative of bridges in the US than any other.

There were different levels of supervision for all three data sets, from the carefully controlled Golden Gate Bridge trips to the unregulated rides on the ride sharing service. The team was able to measure the bridges' modal frequencies from any of the data sets, to within 3% of the readings taken by highly accurate static sensors. It should work with existing data sets from taxi apps, because it means that you can use low-cost, pre-existing data sets.

The data from the phone would probably need to be supplemented with a human. The method could be used on thousands of bridges and only one person would be sent to monitor them.

The researchers estimate that their method could add more than two years of service time to an old bridge and more than 15 years of service to a new bridge by applying maintenance at the right time in a bridge's lifetime.

The journal is titled Communications Engineering.