Infrastructure and IoT: Bridges to the Future

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Infrastructure and IoT: Bridges to the Future

A bridge is the perfect symbol for connection. But, like most links, bridges are highly vulnerable and need constant monitoring to reverse damage caused by normal wear and tear. How do the authorities identify where the biggest problems lie and decide which to throw money at first from their shrinking budgets for infrastructure? The solution: Infrastructure and IoT.

by Knud Lasse Lueth

The traffic infrastructure across Europe is slowly crumbling, and in most cases radical rebuilding is not an option. It’s becoming an incendiary situation but politicians merely fiddle while the roads burn. It seems insoluble. The Minister for Transport in Germany’s most densely populated state of North Rhine-Westphalia uses harsh words to describe the condition of an autobahn bridge connecting neighbors Cologne and Leverkusen. “This is a monument to the desolate condition of German infrastructure,” he fumes. For years, the bridge was a permanent construction site. When it was finished in 1965 it was a proud landmark, with two lanes in each direction and additional breakdown lanes. At that time, it was built to handle 40,000 cars crossing each day.

Infrastructure and IoT: Rheinbrücke Leverkusen - Sperranlagen A1 zur 3,5 t-Gewichtsbesc

Daily ordeal for drivers: Scenes like this are very common around the A1 autobahn bridge between Leverkusen and Cologne.

By 2016, the average number of vehicles per day had increased to 120,000, including at least 14,000 heavy trucks. Besides this, the average weight of each vehicle has also increased since the 1960s. A temporary solution was imposed by banning vehicles over 3.5 tons from crossing at Leverkusen. It merely shifted the problem to other bridges in the area, which now get more than their fair share of stress, and this creates new challenges. The problems can’t be solved by temporary traffic management measures and maintenance alone. In 2016, the decision was made to build a new and much larger bridge next to the old one. The estimated cost for the new construction was then €740m, but as we all know projects of this size have a tendency to go over-budget and schedule. The bottom line is that it will take years and many more Euros to remove this bottleneck. It has become crucial to gather information about the overall state of bridges and roads in the whole region and report or predict possible damage as early as possible – this is, where digital technology can make an entrance on the stage.

Autostrada del pothole

Italy has more highway bridges than any other European country. Inspection is done manually but some of the more critical points where damage usually strikes are hard to reach. To solve this problem and to cut costs, there is a handful of private companies that operate the motorways in Italy. One such is Autostrade per l’Italia, which is responsible for more than 3,000 kms of roads. It has contracted AivewGroup, based in Rome, to undertake surveillance with the help of sensor-equipped drones. The company uses Aibotix Aibot X6 UAV multicopters on 800 of the more than 4,200 bridges on their stretch of the autostrade. These unmanned flying machines are 45cm high with a diameter of just over a meter. Powered by six propellers each, they can lift weights of up to two kilograms, enough for inspection purposes which require them to carry a Sony digital still camera. In the past, engineers had to climb up steep ladders or rappel (abseil) off the bridge, with no guarantee they would be able to see into the more inaccessible spots. The unmanned aerial vehicles (UAVs), as the drones are known, can be maneuvered easily and quickly into tight spaces and under overhangs to take close-up photos of potential damage. The German developer of the drones has added a special camera mount on top of the UAVs to allow closeup inspection under the deck of the bridge and in narrow places. Professional pilots control the multicopters and assure safety beneath the bridge span but the UAVs can do the lesstricky data capture on the sides of each bridge autonomously.

Infrastructure and IoT: Nicola Marietti Aibotix drones

The sky’s the limit: Nicola Marietti and two of his crew members with the Aibotix drones used for bridge inspections.

All the equipment required fits in a small station wagon and the investigation operation only requires a team of two people. A drone capable of doing the job must meet several requirements, not the least the ability to fly reliably in difficult weather and wind conditions. Sometimes they even have to operate close to electricity pylons. The drones normally rely on GPS data to keep on course, but the UAVs often operate close to or underneath bridges where GPS coverage can be limited or blocked. Vision positioning and gyroscope-controlled attitude maintenance (Atti) systems come into their own under these circumstances. In addition, the exact location of where the images were acquired must be recorded if the information gathered is to be of any use for planning future maintenance and repair work. Analyzing the data Gathering the images is a relatively mechanical process; making sense of them is the real challenge. “We have a well-defined and tested procedure in place for more than 6,000 facades,” explains Nicola Marietti, founder of AiviewGroup, “which helps us to understand the problems that might be occurring with the bridge and how to report that to the customer. We use artificial intelligence algorithms and image recognition to allocate a status for different elements of the infrastructure. We check for problems in the cement and iron of the bridge, vegetation, and the environment in general,” he says. The enterprise platform used to manage and monitor customer assets relies heavily on artificial intelligence and predictive analysis, Marietti maintains. “We control the entire workflow of inspection from the planning of the inspection, to the feldwork, to the analysis and reporting. Not only with defect analysis but also 3D models, CAD, and other tools,” he says. Flexible and easy to use, the technology will cause a revolution in surveying techniques, Marietti says. With its unique abilities and the huge amounts of data that can be collected, this approach will surely make its way into other forms of maintenance and surveillance, he suggests. Sensor-equipped multicopters could also be used to detect and capture far more than just images. For example, light detection and ranging (LiDAR) hardware is getting smaller and lighter, allowing the delivery of high accuracy 3D models of inspected bridges, even where there isn’t any construction data available. Thermal sensors could also give interesting input for bridge inspection, and multispectral or hyperspectral sensors would allow analysis of the properties of various bridge materials. Norway has more than 1,800 road bridges nationwide and many are located in the countryside far from any large city. UAV systems builder Orbiton, based near Lillehammer is using drones to inspect these remote sites. The company’s technical director Gonzalo Figueroa says drones make inspections easier and cheaper without disturbing daily traffic. Statens Vegvesen, the Norwegian public road authority, has contracted Orbiton to conduct regular inspections on 80 bridges in the Østlandet region of Eastern Norway, which includes the capital city of Oslo. Prior to 2015, inspections were done with the help of what Gonzales calls “snooper trucks” – vehicles with a flexible crane to move an inspection engineer alongside and underneath the bridges. The vehicles are expensive to buy and costly to maintain. They also cause massive road obstructions so signs need to be erected and staff allocated to direct trafc – in many cases the bridge must be closed down completely for inspections that can take hours. Consequently, the work was often conducted at night, which made it even harder to detect problems. Using inspection drones provided by Ascending Technologies, a German manufacturer, allows Orbiton to do the work during daytime hours without causing any disruption. Instead of needing a team of seven to 10 specialists, a bridge can now be inspected by two staff, and in much less time.

Infrastructure and IoT: Gonzalo Figueroa OrbitonWhat is the biggest benefit of doing bridge inspections with drones?
Employing a Snooper Truck at night like we used to endangers safety regulation and meant we had to at least partially close the road. We also needed a crew of five to ten people to block lanes or the entire road. Now we can do the job with just two, and we can access almost all parts of the bridges quickly and efficiently.

How does this method change the way bridges are monitored?
Engineers who evaluate the results must adapt to doing so only using pixel-based data. In the beginning, engineers tend to be skeptical of this method, but from the experience so far, we see that new skills in evaluating the images are acquired quickly. Engineers feel they are something like doctors using ultrasound equipment to do an analysis. But with our evaluation tool, Unity, which allows a user to access the acquired data online, clients are able to visualize, manage and analyze their drone data, which leads to more reliable results.

What is the biggest problem?
In Norway, bridge inspections have to be conducted in accordance with strict standard procedures that were established long before drones were an option. The official bridge inspection handbook, a 350-page manual, was written many years ago. Inspections of public infrastructure need prior consent by the public authorities – it was even quite hard to get the current project started. It’s now hard to imagine that future developments will be ignored.


Infrastructure and IoT: Fixed sensors

Doing regular inspections at lower cost and with a higher frequency will help detect failing structures earlier. An even better idea, many believe, is to install sensors on the bridges themselves and thus be able to collect information about structural problems To this end, the German Ministry for Traffic and Digital Infrastructure (BMVI) launched a Smart Bridge project last year under its Digitales Testfeld Autobahn (Digital Highway Field Test) initiative. The first ‘intelligent’ bridge was opened for traffic near Nuremburg in Bavaria last October. The so-called Smart Bridge connects two motorways and sensors provide a constant stream of information needed to evaluate its status. Three types of sensors are required to monitor and analyze elements that may affect the bridge: structural integrity, traffic patterns and usage.
The Universität der Bundeswehr München (German Federal Armed Forces University, Munich) in cooperation with Maurer Söhne, an engineering company also based in Munich, developed an Intelligent Track Transition module for the project. These high-end sensors are fitted inside the bridge’s expansion joints to detect vehicle speed, weight, the number of axles and the distance between them. The system can use this data to dynamically calculate axle loadings.

Infrastructure and IoT: Bridges Sensors

Sensors are like eyes and ears: Some examples for the integration of sensors intothe “smart bridge” (Click to zoom).

The Smart Bridge project also includes Intelligent Sensor Networks being developed by the Institute of Telematics at the University of Lübeck to monitor the bridge structure. In addition, a road traffic management system developed in the city of Weimar by the Bauhaus University and civil engineering firm Ingenieurbüro Freundt will gather further traffic data for the analysis. Together the systems build a digital model of the bridge in real time by transferring the data by Wi-Fi locally for testing and calibration. The data will then be beamed over the internet to scientists and maintenance crews using web-based interfaces to view and analyze the collected data in realtime using evaluation algorithms. The current evaluation is expected to take at least five years and the Federal Highway Research Institute (BASt) has high hopes for transferring and applying the results of the test to other new bridge projects as well as to existing structures.

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