70% of bridges are beyond their design life…what can we learn from Genoa?
Over 45,000 bridges in America have been labeled as structurally deficient. 70% of bridges in Australia are estimated to be beyond their design life. At the end of the month, the collapsed Genoa bridge in Italy will be replaced by a new one, but what can be done to prevent tragedy happening again?
In 2014 my family and I were lucky enough to be on a 3 month sabbatical and we drove the roads of the Italian Riviera. It’s an incredible road trip with huge Mediterranean vistas from the tops of impossible bridges. Few of these were as iconic as the Genoa viaduct - the bridge that was designed by Riccardo Morandi and which later would become famous for collapsing.
At the time that my family traveled over the viaduct, tourists like us were blissfully unaware of what locals and academics were starting to realise — that the bridge was weakening. Following multiple studies, Structural Engineer Carmelo Gentile warned Autostrade l’Italia, the company that managed the bridge, that there were troubling signals of corrosion and weakening in the Southern Supports, likely being hastened by the saltwater air and local pollution. Little was done.
Tragedy leads to a determined Italian response
On August 14th, 2018 — just 51 years after it was opened — the bridge collapsed. The bridge failed at the Southern Supports, collapsing 140 feet and killing 43 people.
The news footage that day stunned me. People were on their family vacations just like we had been. They were driving along at 80km/h as a section of the bridge in front of them disappeared.
There has been much public fury over the collapse, not least because of the availability of sensors that could have identified and averted the danger. Since then, after all of the investigations and repercussions, Italy has surprised with the speed with which they have replaced this critical piece of transportation infrastructure. This month, almost 2 years after the collapse, a new ‘Smart’ Genoa Bridge is expected to open to the public.
This Italian tragedy really moved me but my point in reminding people is that we must learn from the experience. It would be too easy to let time erase memories and believe that this could never happen in my country, never on my city’s bridges, and certainly not on my next road trip. Unfortunately it could.
Our ageing infrastructure
Since taking on the role at Confirm, I’ve spent some time trying to understand the ageing infrastructure problem. What I’ve learnt is what many of my colleagues and people in our industry have known for a long time, but that doesn’t make it any less alarming.
According to a report by the American Road and Transportation Builders Association (ARTBA) there are 46,100 structurally deficient bridges in the U.S. And, according to Dr Colin Caprani, a bridge engineer and senior lecturer at Monash University, an estimated 70 per cent of Australia’s bridges are more than 50 years old and beyond their design life.
A typical bridge that you might use today in the U.S. or Australia was likely built under nation building programs in the first half of the last century. Most were never expected to last more than 50 years, have had less than ideal maintenance programs, and the volume and weight of traffic that they now support simply was not expected back then. Put simply, what happened in Genoa could happen to tens of thousands of bridges.
So what can we do to avoid new tragedies?
Carmelo Gentile, the academic that advised of the corrosion in the Morandi viaduct, recommended that detailed computer modelling should be performed along with the installation of permanent sensors. Sensors that could have given early warning signals and may have saved 43 lives.
Gentile was likely talking about Structural Health Monitoring (SHM) which these days can use relatively inexpensive sensors to provide real time monitoring of large structures like bridges and dams. They can provide timely alerts to asset owners when measurements start to stray outside of acceptable thresholds.
The new bridge in Genoa, designed by the One Sydney architect Renzo Piano, implements SHM through hundreds of sensors. They will monitor such things as vibrations, the deformation of the road surface, and the position of the bridge pillars. For the technically minded, it implements internal sensors consisting of accelerometers, strain gauges, velocimeters, inclinometers and detectors of the expansion of joints and differential displacements.
SHM is also being used in major transportation infrastructure such as the Sydney Harbour Bridge and the Brookyln Bridge, but this is atypical. Even though it is relatively inexpensive, most bridges still lack any kind of sensor based alerting, even in new bridge builds.
Economic penalties can also be huge
It’s not just personal safety at risk but also the tremendous economic penalties of lawsuits, economic disruption and repair costs. An example here is the closure of Scotland’s Forth road bridge. No lives were lost but the bridge was forced to close for a whole month when a crack was discovered in a steelwork stiffening truss. The repair costs alone exceeded $3 million but, with 2 million vehicles passing over the bridge each month, the economic impact of closure was far greater.
Early detection and remediation is ultimately much cheaper than the alternative.
“Spending 1 to 5 per cent of the construction cost of a structure on installing SHM during the build can provide minimum to comprehensive levels to monitor structures for timely maintenance.”
— Professor Chan, QUT’s Science and Engineering Faculty
And there’s so many bridges
Another part of the problem is that scaling is not easy. Monitoring key infrastructure bridges like San Francisco’s Golden Gate Bridge or Brisbane’s Gateway Bridge might be worthy of a dedicated analysis and response team but what of the rest? The Australian Local Government Association (ALGA) reports that there are around 30,000 bridges managed by local councils. And the US Department of Transportation calculates that America has 612,677 bridges. Budget for sensor installation aside, how do you operationalize SHM for that many infrastructure assets? That’s a question that my Confirm team are keen to talk about.
Integrating SHM with Infrastructure Asset Management
Infrastructure Asset Management (IAM) is a core I.T. system for government and commercial infrastructure operators. This computer system enables owners to operate and maintain assets like bridges and roads more efficiently — managing maintenance and ad-hoc servicing in order to reduce costs and create more reliable and sustainable environments. Confirm is one such IAM system, managing an estimated 55% of UK Roads and 14% of all assets under the ownership of Australian Local Government.
Leading Infrastructure Asset Management solutions like Confirm are connecting assets through IoT technology. Prior work in this area has been linking smart sensors to such things as bins, storm water drains, and street lighting. You can imagine the cost savings that are possible if you only have to send someone to empty a public bin when it’s nearly full or you can dim street lights when there’s nobody around. But this is the tip of a very large opportunity — our ageing transportation infrastructure can also be integrated directly into these IAM systems. Systems that are already being used to manage the teams that maintain and service the very assets that we want to monitor.
In the above diagram, SHM monitoring is depicted on the left hand side. It is relatively new but already proven in key transportation infrastructure. Technology attached to the monitoring side is becoming more and more sophisticated but it is rarely connected into the established and regular operational work of Infrastructure Asset Management.
The right hand side of the diagram — the world of IAM — is already operational in most of our government and commercial infrastructure operators. This is what systems like Confirm have been doing successfully for decades. They provide software applications for Operational Asset Management like maintenance planning, work scheduling, dispatch and completion. And they also perform Strategic Asset Management such as whole of life cost accounting, depreciation planning, and asset replacement modelling.
Connecting the two will ensure that neither works in isolation and that the regular workflow of the asset owner is integrated and responding to the signs of ageing.
Forward thinking for our ageing infrastructure
Flight Deck instrument monitoring, Root Cause Analysis and Corrective Action Process is commonplace in Aviation to prevent failure from happening again. They have effectively operationalized the process of risk management for millions of flights every year, and we need to think in similar ways for our ageing infrastructure.
The opportunity to connect Strategic Health Monitoring to Infrastructure Asset Management is one way in which we can scale to meet the needs of hundreds of thousands of bridges and other assets. It has the potential to help prioritize and respond to the ageing infrastructure crisis, provide data points for continuous improvement, and potentially prevent tragedies like Genoa happening again.
