“This project is my personal treasure chest as a civil engineer.” – Insights from Stuttgart 21
Tobias Willmer has been with CDM Smith since 2013 and, as a senior project engineer in the Infrastructure and Geotechnics department, is part of Stuttgart 21, PA 1.3a Airport Link. Prior to this, he worked on the project PA 2.2 Albaufstieg, related to the high-speed railway line Wendlingen-Ulm.
Tobias, what are your tasks?
I work in construction supervision as a specialist site manager for tunnels, special foundation engineering and geology. Among others, I also take care of the technical processing of invoicing, measurements as well as supplements. With such a complex project, unforeseen events are inevitable. As a team, we find solutions together and with our clients as well as with the construction companies. I really enjoy coordinating, advising and instructing my colleagues and our professional discourse enriches me.
What is the current construction progress?
We are facing the finish line. Work on the new above-ground line is almost complete. Several bridges, roads and paths were built, major earthworks were executed, rainwater retention basins and noise barriers were erected, and a large variety of other work was carried out. Test runs for commissioning are scheduled for the next months.
Tunnelling work for the underground connection to the airport has also been completed since autumn 2023 and work on the interior construction is in full swing. The focus is currently on constructing the access buildings to the underground railway station. These complex buildings are being installed in the shafts, which are around 30 metres deep. Afterwards, the tracks will be laid in the tunnel tubes so that the technical equipment can follow.
How will “Stuttgart 21” affect the population after completion?
The population will benefit from “Stuttgart 21” and its new line to Ulm. Environmentally friendly rail travel will become more attractive. The new Stuttgart Central Station is not only appealing by its architecture: a new, modern urban district will arise from the huge old railway station site thanks to sustainable and social development.Stuttgart 21 is a trailblazer for environmentally friendly rail transport and intelligent urban development.
Thilo Voigt has been with CDM Smith as a project engineer in the infrastructure and geotechnics department since 2020. Since then, he has been an integral part of the construction supervision team for the Stuttgart 21, PA 1.3a airport connection. To him, this project is very meaningful.
Thilo, what do you do?
My work is very wide-ranging. At the beginning, I was responsible for tunnelling. This involved providing technical support for the conventionally excavated tunnel and monitoring its execution. Approving earthing and testing safety equipment (such as radial anchors) were also part of my daily tasks. The work on the inner shell presented new challenges such as sealing, reinforcement, formwork and concreting. A detailed supervision was necessary as well as regular monitoring, approval or releasing processes for concreting. Coordination within the team, with the construction company carrying out the work and with the client is also one of my core responsibilities.
What have been or are the biggest challenges so far?
Experiencing a major project like this from almost the very beginning is always exciting and very varied. The ever-changing tasks are challenging, promote my personal development and help me to deepen my knowledge. What I like in particular is that, as construction supervisors, we look after more than one construction site at the same time. We must be able to switch directly from tunnelling work to the inner shell, which is extremely complex. But it's precisely this transition from large excavation machines, lots of dirt and noise to the comparatively clean and almost delicate internal formwork labour that is simply fantastic.Not a day goes by that does not teach me something new.
What is particularly fascinating about Stuttgart 21?
The fascinating thing about this project is the overall structure that is being built. For a young civil engineer, it's like a goldmine of experience! Countless different areas of the airport link make it so unique. There are access tubes, railway station, many shafts and expansion structures: each one is breathtaking. Especially the interplay of all these individual structures is indescribable. When you first sink shafts downwards and then later drive the tunnel through the shaft, it is extremely impressive. Even the most experienced foremen on the construction site are amazed at the construction processes and the structures’ harmony. You don't see something like this every day and probably only once in a lifetime. I can only consider myself lucky to be involved in such a major project.
What are the next steps in the project?
The major concreting work inside the tunnel is almost complete. Many of the shafts and the above-ground buildings have been completed in the shell. In the railway station area, the focus is now on constructing the entire platform. The excavation tunnel is barely recognisable anymore and the future station for the public is taking shape. Space becomes narrower and it is becoming clear how much effort and technology is needed to build a tunnel like this. To ensure that it will survive the required 100 years, the focus is and will remain on quality testing. All concreted components must be inspected, assessed and, if necessary, restored to the prescribed condition. There is still a lot to do, and we are looking forward to it.CDM Smith is a privately owned engineering and construction firm providing legendary client service and smart solutions in water, environment, transportation, energy, and facilities. Passionate about our work and invested in each other, we are inspired to think and driven to solve the world’s environmental and infrastructure challenges.