The route is travelled by around 110 long-distance trains every day at high speeds of up to 280 kilometers per hour and connects Hanover with Würzburg through the high-speed line (SFS) 1733. In summer 2020, Deutsche Bahn commissioned SPITZKE SE as the company responsible for the project to refurbish the tracks for around 40 kilometers between Göttingen and Kassel. The tender included 37 kilometers of track renewal, ten kilometers of ballast cleaning, 25 kilometers of ballast recycling and the renewal of 49 points. As the SFS 1733 runs through tunnels for around 21 kilometers – including Germany’s second longest tunnel – SPITZKE SE awarded the planning and execution of the tunnel ventilation to the Essen-based engineering and consulting company DMT GmbH und Co.KG.

Experts understand ventilation to mean as much as aeration: fresh air must be supplied, and harmful gases must be diluted and discharged to ensure healthy and safe working conditions in the tunnels. Because Deutsche Bahn’s tunnels are not equipped with a ventilation system, temporary ventilation was needed for the duration of the construction work. The entire project actually comprised three phases. "At the beginning of October 2020, we started planning the ventilation, which I presented to the clients at the beginning of 2021,” explains Andreas Bischoff, Senior Project Manager Civil & Mining Engineering at DMT and responsible for the project. “After the approval of the detailed design, we carried out the temporary ventilation on site from April to July and for a downstream phase of the construction work in September 2021." Bischoff and his team then implemented the final evaluation and documentation as the third and last phase of the project.

Ventilation on the SFS 1733 challenged DMT’s interdisciplinary team

"This contract is one of the largest projects we have ever undertaken in the field of tunnel ventilation," says Bischoff. Around 30 experts from DMT were temporarily on site, while internally in Essen the Project Management Office supported the project management. "Ventilating tunnels is somewhat less complex than providing ventilation in branched mine pit systems because of the straight pipe flow of the air, but there were enough challenges in this project as well." A key challenge was dealing with the dust from moving ballasts in the track bed. "Having an accredited dust testing center in-house has proven to be an enormous advantage for us. On the one hand, we have access to the knowledge of technical luminaries in-house, and on the other hand, we are not tied to manufacturers and can use project-specific procedures for weathering."

But cooperation with colleagues in the dust testing center was not the only cross-connection to in-house departments. "My colleagues also played an important role with their digital online monitoring system Safeguard," explains Bischoff. "In this way, I could – and still can – look after the construction site 24 hours a day via my laptop without having to be directly on site. Via Safeguard, I can monitor the tunnels at any time, check the air flow and even change the ventilation settings, if necessary.” The data is also available via his smartphone without any time delay, and he saves time in reporting because it is partly automatic.

Ensuring smooth processes for tightly timed planning

Equipped with these capabilities and access to interdisciplinary knowledge, the DMT team were able to meet the time challenge of the project. "It was a tight schedule, and from the very beginning all processes had to run precisely and smoothly. We chose particularly robust fans, because every standstill and track closure would have cost the construction companies money," Bischoff says. "Without my team and the cohesion in DMT, we would not have been able to implement the project so seamlessly.”

For the future, Bischoff and his team plan to operate the measurement technology in a resource-saving way using electricity from solar panels and to extend its services to weathering in road tunnels. Until then, there are already further orders for the ventilation of tunnel structures. "DMT combines capable project management with innovative and flexible expertise. That simply convinced us. With such a tight schedule, the coordination of the respective competences was crucial," says Chris-Adrian Dahlmann, Project Manager at SPITZKE.