To keep our bridges safe and open for many years it’s necessary to monitor them. Today’s inspections are done at regular intervals – and the inspectors’ eyes are the most important tool.
But with the help from sensors their work can be facilitated and more precise.
“Maybe the sensor technology also can provide for an automated warning system that could inform the traffic. For instance, a sign that says “no more heavy traffic” if it is evident that the bridge is under duress,” says Miguel Prieto, researcher at RISE.
RISE has a broad knowledge and expertise within the field of concrete and cement. Tear and wear and active maintenance of constructions like bridges are important topics for the future.
With the help of sensors it is possible to bring in large amounts of data about what is happening in a bridge – in real time. For example, you can measure the deflection of the bridge when exposed to heavy traffic and if there is a significant increase in the deflection, it is an indicator of something affecting the bridge. Also, you can measure the movement of the footing of a pillar after a flood.
“One of the challenges is to interpret all the collected data. Today we can gather huge amounts of information – but is has to be processed to be useful,” says Patrick Fontana, research leader at RISE.
The Swedish transport administration inspects all bridges at least every sixth year. But with a continuous flow of sensor information the inspections could be done with more ease. Furthermore, the sensor systems could be used for prewarning – signaling that something unexpected has occurred that needs an inspection ahead of the scheduled one.
This is not a question just about bridge safety. With the right information about the state of the bridge appropriate actions can be adopted to extend the lifespan of the bridge. The Royal Institute of Technology have monitored the Lidingö bridge with sensors. The sensor monitoring does not intend to replace the normal inspections. But the improved knowledge from the sensors of what’s happening in the bridge have made it possible to hold off the construction of a new bridge. RISE is a part of that program with the expertise from the SICS unit.
Miguel Prieto researcher at RISE has a long experience of studying what indicators to look for when measuring the state of the bridge.
“It’s not a good idea to monitor just for the sake of it. You have to know what you’re looking for.”
Regarding bridge maintenance it is often better to do preemptive maintenance. That is to take action where needed before it becomes a problem. That method can be even more precise with the help of sensors.
“I can see a good use here,” says Miguel Prieto. “In the long run you could also think of a system that works together with the traffic and community. With automatic signs that would notify to slow down if the system detects that the bridge is temporary under stress due to heavy traffic or extreme weather situations.”