BauBots from Fischer master Engelberg tunnel renovation

The Engelberg Tunnel on the A81 near Leonberg is one of the busiest tunnels in southern Germany, with around 120,000 vehicles daily. Two tubes, each 2,530 meters long, handle massive traffic flows towards Karlsruhe and Heilbronn. But beneath the surface lurks a geological problem: anhydrite. This rock swells with moisture and presses against the tunnel ceiling, with devastating consequences for the building structure.

In 350 meters of tunnel, this mountain pressure caused massive damage, necessitating comprehensive structural reinforcement. Measures to strengthen the tunnel linings in the anhydrite-damaged sections include: installing a facing shell of reinforced concrete with steel beams for static bracing of the vaults and installing an intermediate ceiling. Additionally, the roadway slab is reinforced, serving as a transverse brace. At the same time, the safety and operational technology is being renewed throughout the entire tunnel length.

Innovative construction robotics in use

During the renovation, three BauBot robots from Fischer were used. The robot-assisted high-precision drilling technology enabled fast, safe, and precise preparation of anchoring points, especially in hard-to-reach areas in the tunnel vault. The BauBots created more than 9,000 hammer-drilled holes with a diameter of 20 mm and a drilling depth of 240 mm at heights of up to 7.5 m fully automatically in concrete.

BauBot services - the central point of contact for the planning and implementation of Fischer robotics applications on the construction site - coordinated and accompanied the use of the construction robots - from planning through execution to documentation. The services ranged from creating the digital construction plan, which provided the BauBots with the exact drilling points, to accompanying the execution by operators on site to successful completion. The integrated dust extraction of the robots ensured a clean, health-friendly working environment as well as the compliant installation of fasteners in the cleaned drill holes. Drills and consumables were included in the service package. In addition, additional robots, end effectors, and operators were available as replacements to avoid downtime. Each drilling with relevant process parameters, such as drilling depth, reinforcement hits, and other important information, was automatically documented - manual logs were not necessary.

(Source: Fischer)