FOR more than 100 years engineers have been trying to solve the problem of movement on rail and road bridges.

Traffic and wind regularly cause low frequency vibrations to ripple through bridge building materials such as steel and concrete. 

Now, a team of Scots engineers are hoping the oscillations caused by heavy traffic at peak times could actually be used to improve the safety of structures including the Forth Road Bridge and the Queensferry Crossing.

The energy created during vibrations would normally travel away from its source before dissipating.

Academics at Heriot-Watt University alongside US colleagues are hoping to develop the first device of its kind that could harness this energy to power wireless sensors that can monitor the structural integrity of a bridges.

READ MORE: Anger as Queensferry Crossing forced to close for second time in seven weeks due to ice fall 

Engineers can then record multiple measurements, such as vibrations, traffic load, wind and temperature, all at the same time but without the need for specialist infrastructure to be installed at significant cost.

In recent years, wireless sensor technologies have been used extensively but most are limited by the finite life span of batteries and high cost of replacements.

Experts say the continuous energy supply could also reduce the need for replace batteries, which can pose safety risks for technicians on high suspension bridges.

The university has received almost £1million in funding in the UK and the United States to develop and trial the device, alongside academics from Georgia State and the Georgia Institute of Technology in the US

The devices, measuring around 5 – 10cm in length, do not require wiring to an electrical power source and are relatively cheap to manufacture. 

They work by holding a small ball housed within a tube that rolls back and forth as the device absorbs low frequency vibrations. 

As the ball moves, it impacts on non-conductive materials, known as dielectric membranes, located at either end of the tube. When the membrane is stretched, a brief electrical charge is applied but once it returns to its undeformed state, the generated excessive electrical charge can be harvested. 

READ MORE: Award-winning bridge to be replaced after just a decade on site 

This electrical energy is stored in a battery and used to power a sensor capable of monitoring the structural integrity of a bridge.

Dr Yurchenko from the School of Engineering and Physical Sciences at Heriot-Watt University, said: “What we are doing is creating a more efficient and cost-effective solution by harvesting energy that would otherwise be lost.

“It’s something that has never been done before in this way.

“It’s a technology that can be used on any bridge anywhere in the world.

“There are plenty of places where these devices can be fitted to a bridge structure such as on cables, on the pillars, other side of the bridge deck, there really aren’t any limits. 

“What they would usually use are wires to connect all the sensors together which you could imaging for the Fort Road Bridge would take a lot of wires and the batteries don’t last long.”

“For the past 100 years scientists have been fighting adverse vibrations to ensure that bridges are safe.

“This kind of technology also eliminates the risks for technicians having to replace batteries on sensors.”

The team is working alongside Wenzel Consult, an independent company that specialises in bridge sensor technology in Austria and Turkey. 

As the project advances, the scientists say they intend to carry our real-life testing of their prototype on a 32m long highway bridge in northern Austria.

The 57-year-old Forth Road Bridge has around 500 sensors monitoring wind speed, vehicle load and displacement.

READ MORE: Serious road accident closes A82 and leads to ferry delays 

Discovery of a fractured truss-end and corrosion of the bridge’s main suspension cables in 2015, led to the construction of the replacement bridge - the Queensferry Crossing, which was completed in 2017.

This now carries 100,000 vehicles a day, leaving the older structure to carry buses, pedestrians and cyclists.

Professor Igor Belykh, Co-Investigator from Georgia State University, added: “These energy harvesters can be used in bridge damage sensors thereby minimising sensor maintenance/battery replacement and decreasing the associated risks to service personnel on high suspension bridges.”

The scientists say that in the future the same technology could be adapted and used to harvest energy from other vibrating man-made structures and machines.