The future of tunnel construction:

BauBots drill ahead. fischer robots support the reinforcement of the Engelberg Tunnel in Leonberg

The future of tunnel construction:
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Reinforcement of the Engelberg Tunnel in Leonberg

The Autobahn GmbH Southwest branch is currently carrying out comprehensive structural and operational reinforcement of the Engelberg Tunnel in Leonberg (Baden-Württemberg). Three fischer BauBots were used for this. The construction robots drilled more than 9,000 holes with a diameter of 20 mm and a drilling depth of 240 mm at a height of up to 7.5 m fully automatically. This increased the efficiency and precision of fastening tasks.

The Engelberg Tunnel is part of the important transport route of the federal motorway A81 and passes through the namesake Engelberg north of the Leonberg Triangle. With around 120,000 vehicles daily, it is one of the busiest motorway tunnels in southern Germany. The two tunnel tubes are each 2,530 meters long and feature three lanes plus a hard shoulder towards Karlsruhe/Munich in the west tube, and also three lanes plus a hard shoulder towards Heilbronn in the east tube. The current tunnel was originally constructed from 1995 to 1999 as a replacement for the old Engelberg Tunnel dating from 1938.

Over the years, mountain pressure caused damage – about 180 m in the western tube and about 170 m in the eastern tube are affected. Geological challenges exist in the anhydrite rock, which swells upon contact with moisture and deforms the tunnel linings as well as endangers the structure. The complex reinforcement is carried out under ongoing traffic while maintaining all lanes and thus in the tightest space – made possible by an elaborate construction site traffic concept. Closures occur exclusively during low traffic times. In the course of the construction measure, the operating technology is completely renewed at the same time, while safety must nevertheless be ensured 100 percent. The complete renovation began in April 2019, completion is planned for 2026. The client is the Federal Republic of Germany, represented by the Autobahn GmbH, Southwest branch.

Measures to reinforce the tunnel inner linings in the anhydrite-damaged sections include: the installation of a reinforced concrete lining with steel beams for the static stiffening of the vaults and the installation of an intermediate ceiling. Additionally, the roadway slab, which serves as transverse bracing, is reinforced. At the same time, the safety and operating technology is renewed along the entire tunnel length. 

Project Brief Engelberg Tunnels in Leonberg

Client:
Federal Republic of Germany, represented by Autobahn GmbH, Southwest Branch
Project duration:
Start April 2019 - planned completion 2026
Project Scope:
Fully automatic drilling of 9,000 drill holes with a diameter of 20 mm and a drilling depth of 240 mm at a height of up to 7.5 m
Reason for renovation:
Mountain pressure damage – about 180 m in the west tube and about 170 m in the east tube are affected
Learn more about BauBot

Innovative Construction Robotics by fischer in Action

On behalf of the renowned tunnel construction company Baresel, the project participants deployed three fischer BauBot construction robots. The robot-assisted highly precise drilling technology enabled quick, safe, and accurate preparation of anchoring points – especially in hard-to-reach areas within the tunnel vault. The BauBots fully automatically created a total of more than 9,000 hammer-drilled holes with a diameter of 20 mm and a drilling depth of 240 mm at heights up to 7.5 m in concrete. 

The BauBot Services GmbH – the central contact point for the planning and implementation of fischer robotics applications on the construction site – coordinated and supervised the deployment of the construction robots – from planning through execution to documentation. 

fischer’s services ranged from creating the digital construction plan, which gave the BauBots the exact drilling points, through supporting the execution by operators on site, to the successful completion. The integrated dust extraction of the robots ensured a clean, health-friendly working environment as well as compliance-compliant installation of the fastening elements in the cleaned drill holes. Drill bits and consumables were included in the service package. Additionally, extra robots, end effectors, and operators were available as replacements to avoid downtime. Each drilling, with relevant process parameters such as drilling hole depth, rebar hits, and other important information, was automatically documented – manual protocols were not necessary. 
Baubot wall
The deployment of our three fischer BauBots contributed significantly to increased efficiency and quality improvement in the renovation of the Engelberg Tunnel.
Emil Kral, Managing Director of BauBot Services GmbH
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