Quattro Expertise deploys smart measurement in dike reinforcement of the city of Tiel

The dike reinforcement of the city of Tiel involves the necessary risks. The many buildings, including several monumental buildings, require the necessary precautions to prevent damage. Quattro Expertise was engaged to monitor this. This included the use of satellite data, a relatively new monitoring method for mapping risks in advance of dike reinforcements.

It is in the interest of the parties involved to build harmlessly and protect the monumental buildings during the dike reinforcement work at Tiel. The buildings are therefore continuously being watched and monitored. Quattro Expertise from Oosterhout was involved because it dares to think outside the box, comes up with cost-efficient solutions and has an eye for a good relationship with residents. "Dijkversterking Stad Tiel is one of the larger dike reinforcements where we have shown that smart measurement is also possible," says Johan Brouwers, team leader research and consultancy. "Nice example of this is the deployment of INSAR measurements from satellites. Height measurements had to be started a year before the work started to gain insight into the average subsidence rate. However, that time was not feasible. We then proposed the solution of using satellite data. The advantage of satellite data is that you gain insight up to 7 years back and in a short time you have much more data than with height measurements. Thanks to these measurements, we were able to detect a number of properties with an increased risk of subsidence, including the well-known Grand Café Bellevue."

Good communication local residents

The affected properties at increased risk of subsidence are equipped with tilt sensors. These measure small changes from the horizontal level both on the ground and in structures. "This is a cost-effective measurement method because it is unmanned measurement. So there are fewer surveyors coming to people's homes, which is nice for local residents because measurements often had to be made in backyards. Only where necessary do we deploy people. We established good contact with the residents beforehand. We also gave explanations during the organized residents' evenings. We find that very important, because with good communication and explanation of what you measure and how you do it, you can prevent a lot of possible misunderstandings during the process." Quattro has even developed a special app that allows residents, exceptionally, to do a simple architectural survey themselves. "We only deploy these when home visits from our surveyors are not possible. In corona time, we developed this app because we were then limited in personal measurements at people's homes."

Highly accurate

Another measurement method employed is inclinometer measurement, also known as slope angle measurement. "We apply this method in the installation of the combi wall construction at the level of Grand Café Bellevue. We need to know at all times how the ground is behaving at the time of earthworks. With a manned digital inclinometer, we can measure displacements very accurately to a depth of 20 meters."

Real-time measurements

All measurements take place real-time or manned. Main contractor FPH Ploegmakers receives daily insight into the results. "The cooperation goes well. Every week our project leader is on site to watch and make timely adjustments when necessary. Thanks to all the measures and measurements before and during the work, we have not had any peculiarities so far
in subsidence."