‘Like painting the Forth Bridge’ is a phrase that refers to any routine task that seems never ending. The iconic landmark was famous for the challenges of its maintenance regime.

But the new Forth bridge in Scotland, the Queensferry Crossing (opened August 2017), presents a very different picture. Instead of endless routine maintenance, it benefits from advanced health monitoring to make interventions much more targeted.

The result is smoother running of traffic on this critical piece of infrastructure.

Arup has built on its experience in other road bridges around the world, particularly Stonecutters Bridge in Hong Kong, to devise a sensor-based monitoring and safety evaluation system designed to spot potential problems before they happen. 

About two thousand sensors have been installed on the Queensferry Crossing, carefully positioned to monitor the global behaviour of the bridge and its environment in real time. All data will be stored on the cloud to allow analysis and identification of trends in behaviour. This will allow the operator to respond quickly to extreme events, to target inspections, and to carry out pre-emptive interventions to avoid potential failures.

An event-driven system

The sensors make up a system that monitors the wind, the weather, temperature, corrosion, motion and any strains on the bridge. So, if there has been an 80 MPH wind overnight, the system will raise the alarm and calculate where the likely impact will have been and what may need to be checked. 

The monitoring system provides immediate support to the inspectors for remedial maintenance work, as well as long term data that can be analysed and ensure better investment decisions are made.