Smartphones have evolved as Swiss Army knives of technology with capabilities that extend far beyond phone calls, selfies and map directions. With the appropriate apps, these mobile devices can provide health and wellness monitoring, access news and music, and enhance productivity at work. They can also serve as structural engineering tools: crowdsourced data from the smartphones of vehicle passengers crossing bridges may help monitor bridge structural integrity.

Bridge vibration frequencies can be identified from smartphone-vehicle trip data in real-world conditions, and as few as 100 crowdsourced datasets can produce useful modal frequency estimates for both short-span and long-span bridges. The Android-based mobile phone application was devised by researchers from Singapore-MIT Alliance for Research and Technology, Lehigh University and MIT to collect accelerometer data when the devices were placed in vehicles passing over a bridge. The data were compared with that recorded by sensors on bridges themselves, to see if the mobile-phone method worked.

To demonstrate this tool, researchers collected smartphone data from controlled field experiments and uncontrolled Uber rides on California’s Golden Gate Bridge and developed an analytical method to recover modal properties accurately. The method was also successfully applied to crowdsourced data collected on a short-span highway bridge in Italy.

a) Sensor layout on the dashboard of the first vehicle used to collect data for the first 50 trips, and b) Sensor layout on dashboard of the second vehicle used to collect data during 52 trips across the Golden Gate Bridge. Source: Commun Eng 1, 29 (2022)a) Sensor layout on the dashboard of the first vehicle used to collect data for the first 50 trips, and b) Sensor layout on dashboard of the second vehicle used to collect data during 52 trips across the Golden Gate Bridge. Source: Commun Eng 1, 29 (2022)

For 10 particular types of low-frequency vibrations measured by as few as 100 crowdsourced datasets, there was a close match with stationary sensor data, and in five cases, there was no discrepancy between the methods at all.

The mobile device monitoring technology described in Communications Engineering could help extend the service life of such structures.

To contact the author of this article, email shimmelstein@globalspec.com