The future of tunnelling:

BauBots drill ahead. fischer robots support upgrading of the Engelberg tunnel in Leonberg

The future of tunnelling:
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Engelberg Tunnel upgrade in Leonberg

Autobahn GmbH’s Southwest branch is currently carrying out a comprehensive structural and operational upgrade 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 main road of the A81 motorway and crosses the Engelberg, which gives it its name, north of the Leonberg triangle. With around 120,000 vehicles a day, it is one of the busiest motorway tunnels in southern Germany. The two tunnel tubes are each 2,530 metres long and have three lanes plus pedestrian crossings in the western tube towards Karlsruhe/Munich and three lanes plus pedestrian crossings towards Heilbronn in the eastern tube. The current tunnel was originally built from 1995 to 1999 as a successor to the old Engelberg tunnel from 1938.

Over the years, rock pressure caused damage - about 180 m in the West Tube and about 170 m in the East Tube are affected. Geological challenges lie in the anhydrite rock, which swells when exposed to moisture, deforming the tunnel shells and endangering the structure. The complex refurbishment is carried out in continuous traffic with all lanes maintained and thus in the tightest possible space - made possible by a sophisticated construction site traffic concept. Closures only take place during low-traffic times. As part of the construction measure, the operating technology will be completely renewed at the same time, although safety must still be guaranteed to 100 percent. The complete renovation began in April 2019 and is scheduled to be completed in 2026. The client is the Federal Republic of Germany, represented by Autobahn GmbH, Southwest Branch.

The measures to reinforce the tunnel inner shells in the anhydrite-damaged sections include: the installation of a reinforced concrete shell with steel beams for static reinforcement of the vaults and the installation of a false ceiling. In addition, the road surface is reinforced, which serves as a transverse stiffener. At the same time, the safety and operating technology will be renewed over the entire length of the tunnel. 

Engelberg tunnel project profile in Leonberg

Building owner:
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 holes with a diameter of 20 mm and a depth of 240 mm at a height of up to 7.5 m
Reason for renovation:
Rock 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 from fischer in use

On behalf of the renowned tunnelling company Baresel, the project participants used three fischer BauBot construction robots. The robot-assisted high-precision drilling technology enabled fast, safe and precise preparation of anchor points - especially in hard-to-reach areas in the tunnel vault. The BauBots 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 a height of up to 7.5 m fully automatically in concrete. 

BauBot Services GmbH - the central point of contact for the planning and implementation of fischer robotics applications on the construction site - coordinated and supported the use of the construction robots - from planning to execution to documentation. 

fischer’s services ranged from the creation of the digital construction plan, which specified the exact drilling points to the BauBots, to the supervision of 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 approval-compliant installation of the fasteners in the cleaned drill holes. Drill bits and consumables were included in the service package. Additional robots, end effectors and operators were also available to replace them to avoid breakdowns. Every hole with relevant process parameters, such as hole depth, rebar hits and other important information, was automatically documented - manual records were not necessary. 
Baubot wall
The use of our three fishery BauBots made a significant contribution to increasing efficiency and improving quality in the renovation of the Engelberg tunnel.
Emil Kral, Managing Director of BauBot Services GmbH
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