Carola Wieser and Markus Wessels are making Munich’s underground safe
“Roughly speaking, you could picture the whole thing as a kind of shoebox. A pretty big one, of course, which also happens to be far below the earth’s surface.” These are the words that Markus Wessels uses to describe what, since 2019, he and Carola Wieser—along with their colleagues—have been building in the heart of Munich. What he’s actually talking about is the new Marienhof S-Bahn (urban rail) station. It consists of a six-story building, but one that’s only being constructed underground. It is there, on the lowest “floor” at a depth of around 40 meters, that the “shoebox” is being built: in other words, the station inclusive of platform tubes. The main task of the duo—he, a geoinformatics engineer and she, a geologist—is to observe the impact of the construction work in the middle of the Bavarian state capital on the surrounding area. The division of labor is clear: one delivers the data, the other evaluates them.
What the installation of measuring points has to do with the north German greeting of “Moin”
Surveys and geomonitoring—i.e. monitoring changes to the surrounding area—begin long before the drills and diggers start up. Measuring points are installed up to a year in advance. This makes it possible to identify the seasonal impacts on the soil, buildings, etc. “In this way we determine in advance which developments have nothing to do with the energetic digging that’s going on now,” Wessels explains. The native of Papenburg has been working with HOCHTIEF since 2007, and has worked abroad a great deal, including in Scotland. He helped to establish BIM (Building Information Modeling) at HOCHTIEF. This work method stands for the networked planning, construction and management of buildings and other built structures with the help of software and 3D models. One of his greatest personal “successes” at the moment: Markus Wessels has firmly established the north German greeting of “Moin” (hi/hello) within the HOCHTIEF team and the Marienhof joint venture in the Bavarian metropolis.
Teamwork: Thousands of measuring points converted to sensitive computer data
Once the data from thousands of measuring points in and around buildings, on the streets and in the construction pit walls have been sent, logged, and approved by Wessels as usable, they go to Carola Wieser’s PC. The teamwork starts, and Carola Wieser takes over. The work of the geological engineer, who graduated in the area of (underground) rock mechanics and tunnel construction has a young daughter, and has worked for HOCHTIEF since 2017, goes hand in hand with that of her colleague: “The client, Deutsche Bahn, has specified threshold values. This means that an existing built structure or the subway route can subside or distort by up to x millimeters,” Wieser explains. However, if despite every care being taken, subsidence or distortions are identified outside the respective norm, an alarm is triggered automatically. “If that happens, we would sit down with the construction supervisor and the client, precisely analyze the values, and discuss how to proceed.” In addition, every week a report is sent to the client, as well as to the municipal utilities, inspectors, experts and supervisory authorities, breaking down all of the important data. This too is Wieser’s job, who also has a “sideline” of monitoring the groundwater which, as part of the construction work, has to be lowered over a large area, and its surface tension reduced.
Nothing beats face-to-face dialogue
Once or twice a week, Markus Wessels travels around Munich’s streets and its subway to see if all of the measuring technology he has put in place is working properly. He checks to make sure that nothing is damaged, and that no cables have been cut. Carola Wieser often joins him on these tours “to better understand where the data that I deal with every day actually come from.” The two HOCHTIEF colleagues work together in an office in a construction container with a view of the construction site in Munich’s old town. To the rear, the Neues Rathaus (New City Hall) towers over them. Wieser and Wessels agree: “Sharing an office makes things far easier. Constantly talking to each other is really important in our job, and it works best when we talk face-to-face.”