Renovation of the Engelberg Tunnel – Automated Drilling Operations With Construction Robots
Autobahn GmbH‘s Southwest branch is currently carrying out comprehensive structural and operational renovations on the Engelberg Tunnel in Leonberg (Baden-Württemberg). Three Fischer BauBots were used for this project. The construction robots drilled more than 9000 holes with a diameter of 20 mm and a depth of 240 mm at a height of up to 7.5 m fully automatically. This increased efficiency and precision in fastening tasks.
Three Fischer BauBots drilled over 9000 holes with a diameter of 20 mm and a drilling depth of 240 mm at heights of up to 7.5 m in the Engelberg Tunnel in a fully automated process
Credit/Quelle: fischer
Deformations Caused by Swelling Anhydrite Rock
The Engelberg Tunnel is part of the important A81 federal highway and crosses the Engelberg mountain north of the Leonberg interchange. With around 120 000 vehicles
passing through every day, it is one of the busiest highway tunnels in southern Germany. The two tunnel tubes are each 2530 m long and have three lanes plus a hard shoulder in the west tube towards Karlsruhe/Munich and in the east tube towards Heilbronn.
The current tunnel was originally built between 1995 and 1999 as a replacement for the old Engelberg Tunnel, which dated from 1938. Over the years, pressure from the surrounding rock caused damage – approximately 180 m in the west tunnel and approximately 170 m in the east tunnel are affected. Geological challenges exist in the anhydrite rock, which swells when it comes into contact with water. The consequences of this expansion are deformations of the tunnel lining and a structural hazard to the tunnel.
Reinforced Concrete Facing Shell for Structural Reinforcement of the Vaults
The complex renovation work is being carried out in a very confined space during ongoing traffic operations, with all lanes remaining open. This is facilitated by a sophisticated construction site traffic management plan. Road closures are only implemented during periods of low traffic. In the course of the construction project, the operating technology is also being completely renewed, while ensuring that safety is fully guaranteed at all times.
The complete renovation began in April 2019 and is scheduled for completion in 2026. Measures to reinforce the inner tunnel lining in the sections damaged by anhydrite include the installation of a reinforced concrete facing shell with steel girders for structural reinforcement of the vaults and the installation of an intermediate ceiling. In addition, the roadway slab, which serves as transverse reinforcement, is being reinforced. At the same time, the safety and operating technology is being renewed along the entire length of the tunnel.
9000 Hammer-Drilled Boreholes
On behalf of the renowned tunnel construction company Baresel, the project team used three “fischer BauBot” construction robots. The robot-assisted drilling technology enabled fast, safe, and precise preparation of anchor points, even in areas of the tunnel vault that were difficult to access. The BauBots automatically created more than 9000 hammer-drilled holes with a diameter of 20 mm and a drilling depth of 240 mm in the concrete inner lining at heights of up to 7.5 m.
BauBot Services GmbH – the central point of contact for all aspects of planning and implementing Fischer robotics applications on the construction site – coordinated and supervised the use of the construction robots, from planning and execution to documentation of the drilling work performed.
Fischer‘s services included creating the digital construction plan, which specified the exact drilling points for the BauBots, as well as supervising the execution by operators on the construction site until completion.
The robots‘ integrated dust extraction system ensured a clean, healthy working environment and the approval-compliant installation of fasteners in the cleaned drill holes. Drills and consumables were included in the service package. Furthermore, additional robots, end effectors, and operators were available as replacements to avoid downtime. Each borehole with relevant process parameters, such as borehole depth, reinforcement hits, and other important information, was automatically documented – manual logs were not necessary.
Enhanced Efficiency and Improved Quality for the Renovation
“The use of our three BauBots contributed significantly to increased efficiency and improved quality for the renovation of the Engelberg Tunnel,” said Emil Kral, Managing Director of BauBot Services GmbH. “This project highlights the enormous potential of modern automation solutions in infrastructure construction.”
The comprehensive upgrading and technical modernization of the Engelberg Tunnel will ensure the long-term performance of a central transport axis. The combination of well-thought-out planning, specialized execution, and innovative robotics makes this project a pioneering example in the field of tunnel construction and renovation.
