Real-time bridge asset management: the future of bridge management

Bridges, locks and viaducts designed and built decades ago are gradually approaching the end of their original design life. But when does a structure really need to be replaced? And how can you be sure that a bridge is still safe to use? Iv’s new real-time assessment system (RTA) gives asset managers continuous insight into the actual loads and condition of their structures. By combining sensor data with advanced computational models, the system provides an accurate picture of a bridge’s remaining service life.

From design assumptions to actual bridge loads

Consider a provincial bridge designed thirty years ago for an anticipated traffic volume comprising a certain number of cars and lorries each day. A few years later, a large industrial estate opens nearby. As a result, traffic patterns change completely. There are more vehicle movements, larger and heavier lorries, and loads far exceeding those allowed for in the original calculations.

“New bridges are designed on the basis of future projections,” explains Garry Vandeburg, Senior Consultant at Iv. “The design process predicts how much traffic will use the bridge and how heavy that traffic will be. But what happens if reality does not match those assumptions?” The actual loads may be considerably higher than anticipated, or much lower. Yet maintenance and replacement decisions are still often based on calculations made decades ago. “For many asset managers, this is one of the greatest challenges they currently face,” says Garry Vandeburg.

Inspections involve extensive manual work

Assessing the structural condition of a bridge requires regular inspections and additional calculations. This often starts with extensive desk research. Engineers gather and analyse drawings, calculations, inspection reports and maintenance records to build the most complete possible picture of the structure.

Further investigations may then be required, such as load testing or taking samples from structural components for laboratory analysis. These methods provide valuable information, but they also have limitations.

“An inspection is essentially a snapshot,” says Garry Vandeburg. “You visit a bridge, take measurements and make an assessment based on what you observe at that particular moment. This takes time and costs money. Sometimes part of the bridge even has to be closed, causing considerable disruption.”
Additional inspections, investigations and reviews of historical records are costly. At the same time, nobody wants to compromise bridge safety. “As a result, structures are sometimes renovated or replaced earlier than is technically necessary, while other bridges require more attention than initially anticipated,” says Garry Vandeburg. “Consequently, maintenance budgets and investigation resources are not always directed to where they are needed most.”

Manual measurements during bridge inspection of a riveted steel structure

Real-time measurement, monitoring, analysis and forecasting

Iv developed its real-time assessment system (RTA) to provide continuous insights into how a bridge or other structure behaves in practice. Permanent sensors installed on the structure continuously collect data on actual loads and structural behaviour. “We are making bridges and locks smart,” explains Garry Vandeburg. “Instead of taking occasional measurements, we continuously collect information about the loads acting on the structure and how it responds.”

The process consists of four key elements: measurement, monitoring, analysis and forecasting. Sensors at strategic locations record deformation, strain and loads. The resulting data is automatically connected to a digital computational model, which is continuously updated with new measurements. “You can compare it to an advanced set of weighing scales,” says Garry Vandeburg. “The sensors provide the input, and the computational model translates that data into information about the condition of the structure.” This creates an up-to-date and increasingly accurate picture of how a bridge or lock actually behaves and what its remaining service life is.

How does RTA work?

Iv’s real-time assessment system (RTA) combines high-frequency fibre-optic sensors with advanced finite element models (FEM). A digital computational model is developed for each structure. The structure is divided into thousands of small elements, providing a detailed picture of how forces, stresses and deformations are distributed throughout it.

The fibre-optic sensors continuously measure how the structure behaves in practice. Even minimal deformation and material strain can be detected through changes in the light signals travelling through the optical fibres. The measurement data is automatically fed back into the FEM model. By continuously comparing real-world measurements with calculated values, the system builds an increasingly accurate picture of the bridge’s actual condition and the rate at which fatigue is developing. In effect, the model learns how the bridge behaves under today’s traffic intensity rather than the traffic for which it was originally designed.

Every structure tells its own story

No two structures are the same. “Every bridge or lock has its own design, and every design has its own critical details,” says Garry Vandeburg. “Some components are barely susceptible to fatigue, while others require particular attention.” A dedicated digital model is therefore developed for each structure. Sensors are installed at strategic, readily accessible locations, such as on the primary load-bearing structure. The computational model then acts as a network of virtual sensors for the entire structure, including locations where physical measurements would be difficult or virtually impossible. “You gradually learn to recognise every creak and groan of the structure,” says Garry Vandeburg.

Although the first applications focus primarily on bridges, the principle can be applied more widely. Locks, movable structures, and even lifting or container cranes can be monitored and analysed in the same way. The underlying principle is the same: the better asset managers understand how a structure behaves in practice, the better they can plan its maintenance, renovation and replacement. “This is only the beginning,” says Garry Vandeburg. “Ultimately, we will be able to apply this approach to an increasing number of structures and types of infrastructure. For new structures, we can even incorporate the system from the outset.”

"A robot vacuum cleaner knows when your home needs cleaning, and a smart thermostat makes sure it is warm when you return. So why should bridges and locks continue to rely solely on historical records and periodic inspections?"

Garry Vandeberg | Senior Consultant

Bringing everything together in one integrated system

More and more systems around us are becoming smarter. So why should bridges and locks continue to rely solely on historical records and periodic inspections?

As far as Iv is concerned, that time has passed. The real-time assessment system is already being applied to an aluminium test bridge equipped with sensors and monitoring technology. Engineers, structural engineers, inspectors, data specialists and machine-learning experts are working together on its further development. Students and researchers from technical and mathematical disciplines are also contributing.

“Sensors, inspections and computational models have all existed for some time,” says Garry Vandeburg. “The real innovation lies in bringing all these elements together in a single integrated system.” According to Garry Vandeburg, this integrated approach represents an important next step in managing civil engineering structures, with potential applications beyond bridges and locks. “I am convinced that this is the future of the replacement and renovation programme in the Netherlands.”