IoT Sensors Monitor Sydney Harbour Bridge Health

Managing large and aging infrastructure assets, such as the Sydney Harbour Bridge, throw up a unique set of challenges in terms of asset integrity, safety, inspections and maintenance, especially when you consider its incredible statistics…

Facts and Stats

Before the bridge was officially opened in 1932, construction had started 9 years prior meaning some parts of the structure are over 95 years old. It’s the world’s tallest steel arch bridge at 134 metres high and the sixth longest single spanning arch at 1,149 metres. Up to 2012 it was also the world’s widest long-span at 48.8 metres. Its usage and load has increased massively over the years. In 1932 an average of 10,900 vehicles crossed it daily compared to today when there can be in excess of 160,000.

Then there is the steel itself. Despite it being our most-used alloy for civil structures, it suffers the most damage (oxidisation leading to rust) through exposure to the elements and must be painted regularly to seal it from the atmosphere. The steelwork weighs in at 52,800 tonnes and has a surface area of 485,000 square metres – the equivalent of 60 football fields. Just one coat requires 30,000 litres of paint. The bridge also contains 6 million hand-driven rivets which must be closely monitored as they risk water pooling and seeping into the structure. What is more, the top of the arch can rise and fall up to 18cm and expand and contract by 42cm due to changes in the temperature and environment.

The Cost and Risks of Visual Inspections

As a result, inspecting the bridge for signs of stress, corrosion and defects, such as rust or cracks, requires highly-trained personnel and significant budgets from its owner, the NSW State Government. Workers have needed to regularly climb gantries to carry out visual inspections, use cherry pickers for hard to access locations, and abseil down the sides using ropes to examine the underside of its deck all whilst hanging themselves 50 metres above the water. There are also over 7 kilometres of small tunnels throughout the arch that workers have had to enter at great risk to personal safety – that is until the development of a new climbing robot that can navigate the complex passageways and relay video back to control rooms.

2,400 IoT Industrial Smart Sensors Deployed

IoT technology is now being leveraged to address some of these challenges. The CSIRO’s Data61 team have developed a structural health monitoring solution and have so far deployed around 2,400 industrial smart sensors across the bridge to capture and relay vibration data.

It is a bridge’s deck that works the hardest and is most vulnerable to damage, especially ageing bridges that must cope with increased traffic volumes and heavier loads. The new system measures the vibrations of the bridge at various points and runs a check on these signatures – because when there is a physical change in the structure such as a defect or crack, the vibration signature will be different.

Maintenance crews looking after Sydney Harbour Bridge can now keep check on the structure via these sensors 24/7 using a web-based interface. When a vibration signature falls outside of normal ranges, alerts are automatically generated and sent via email and SMS. Additional benefits are the ability to get a better sense of what is going on inside the structure and be alerted to issues before they appear, unlike visual inspections that can only see what’s happening on the outside. The new system will also help reduce maintenance costs, improve worker and ultimately, public safety.

Becoming Smarter Over Time

It is predicted that the system will become smarter over time due to the integration of additional sensors to monitor different aspects of the bridge’s behaviour, and the development of algorithms that will recognise patterns over time. For example, as our climate warms, engineers will be able to study the impact that increases in temperature will have on vibrations (which is currently unknown) over time – vibrations which affect the bridges joints and flexes – so engineers can take appropriate action, in a much more timely manner.

World-Wide Applications

The potential for smart sensor technology, and the systems that can tap into them, is significant. There are many bridge assets across developed countries that are all in the latter stages of their lifecycle. More than half of Europe’s 1 million bridges are apparently beyond 50 years of life. Earlier this year we saw the devastating impact of a bridge failure in Genoa, Italy which resulted in significant trauma and loss of life. Here in Australia around 70% of our bridges are more than 50 years old. Against the backdrop of this aging infrastructure there is continual pressure to allow heavier vehicles and increased traffic volumes. Perhaps automated sensing solutions will one day be mandated across all aging infrastructure assets to further extend their return on investment, safe use and life.

An Intelligent Platform For Aging Infrastructure Assets

This project is a great example of how LPWAN sensors, something we’ve written about previously, and smart cloud and mobile computing power can improve the way owners and operators manage their assets more thoroughly, productively, cost-effectively and safely.

assetDNA is a web-based enterprise asset intelligence solution that can be used for asset monitoring and automated inspections. It includes:

Asset Tags and Sensors – assetDNA is built to work with any Barcode, RFID, NFC, DPM, BLE, IoT, RTLS, GPS, covert security, and more, as well as multiple technologies simultaneously, and which can be used to capture and relay data on humidity, temperature, expansion, tension, vibration, volumes and loads.

Serialisation and Asset Data Management Software – Which receives the readings from the sensors, associates data with assets, sends threshold alerts to key stakeholders, feeds data to other systems and produces dashboards and reports.

Mobile Applications – User-configured mobile workflow and data capture applications for visual inspections, physical asset audits, maintenance, work orders, risk and control assessments and more.

Reader Hardware and Devices – Smartphones, sleds, rugged hand-held PDA’s, fixed readers, gantry’s, weighbridges, drones, tablets, kiosks, touchscreens.

With these components, which work together as a cohesive whole, asset owners can create current, clean and complete digital profiles of any asset, down to a component level; in any business context; enrich these profiles with real-world, real-time data; pass data to other systems, and leverage insight to trigger better decisions and faster action. Furthermore, assetDNA’s platform is completely open and flexible so that sensors, tags and equipment, and data capture models can be tailored to the unique requirements of each individual bridge.

For asset owners and operators around the world tasked with looking after aging infrastructure, assetDNA can be integrated with a broad-range of smart sensor technology, deployed to monitor performance, and deliver to stakeholders the data they need to make better, more timely decisions that ensure integrity and safety. Relegen’s asset data management platform also provides the foundation for maintenance to be based on actual condition, rather than time or predictions, increasing productivity, reducing costs, and extending asset use and life.

If you would like to learn more about these capabilities, feel free to reach out to Relegen via or +61(0)2 9998 9000.