Clifton project demonstrates open source software for structural monitoring

Author : Steve Dale

Researchers at the University of Bristol are engaged in a project to demonstrate the viability of using free open source visualisation software for structural health monitoring on the Clifton Suspension Bridge.

The project recently garnered attention after structural data was used to create music, which was then played on a double-strung harp using two robotic arms in a unique experiment.

Streams of data were collected from wireless sensors that were installed on the 150 year old bridge for one month in January this year. The researchers were able to display these data streams in near real time using open source software Grafana, a “data dashboard” which is typically used by the IT industry to monitor server farms.

A further sensor deployment is expected to take place next year, explained engineering mathematics PhD student Sam Gunner, who has led the project. “Rather than a long-term deployment of sensors we were keen to do something that could be rolled out cheaply and get a full profile of the structure and how it moves, for however long the batteries last.

“The idea is that you pick up all vibrations over the bridge while also measuring wind speeds and traffic flow to get a full picture for, say, a month. Then you can come back a year later and run the same experiment.” The two monitoring periods can then be compared to detect any changes that might indicate structural ageing or fatigue.

Hardware installed on the bridge had to be cheap to meet the project’s £5,000 budget. “Almost all the technology we used was off the shelf,” said Mr Gunner. This included four strain gauge accelerometers to measure vibration and two potentiometer-based displacement transducers to measure the rise and fall of the bridge. These were placed strategically along the structure.

Civil engineers are currently studying the data collected from the first deployment of sensors. While just six sensors were needed to monitor the Clifton Suspension Bridge, the technology can be scaled up to measure vibrations and displacements on far larger bridges, Mr Gunner explained.

The devices were connected to wireless sensor nodes which in turn communicated with an outstation beneath the bridge. Here a message broker stored and transmitted the data into a time series database, which would periodically be queried by the Grafana visualisation software.

This software potentially allows the data to be displayed to structural engineers or bridge management personnel in real time, anywhere in the world.

Following the initial technology deployment in January, Bristol-based musicians and sound artists Yas Clarke and Lorenzo Prati created an installation to musically represent the structural data collected.

The harp project was developed by the Jean Golding Institute at the university. Sam Gunner commented: “To see our research represented in this way is really remarkable. The Clifton Suspension Bridge is a much loved sight and now people can both see and hear it in a new light.”