System Convinces by Cost Effectiveness: Mittlerer Ring,Munich

The Mittlere Ring is one of Munich’s main arterial roads and is known for its very heavy traffic. Some of the bottlenecks of the multi-lane road that circles the city center have previously been eliminated by the addition of new tunnels. One of them being Luise-Kiesselbach Square.


Luise-Kiesselbach Square is the last section of this road improvement effort. The square is an important traffic hub in the southwest of the city. Here, motorways A 96 from Lindau and A 95 from Garmisch meet, causing long delays in daily rush-hour traffic.

The 398.5 Million Euro construction project will consist of a 1,500m long, partly two-level tunnel leading to the A 95 motorway, a 400m long underpass as well as a 620m long tunnel in the eastern section.

Thanks to convenient approach roads, the extension of the Mittlere Ring will considerably relieve the traffic congestion in this area and improve living conditions for local residents by redirecting traffic underground and creating a new park. Construction work began in October 2007 and is scheduled for completion in 2015.


In order to minimize disturbances for the residents, the new section is primarily being constructed using the cut-and-cover method. Initially, piped vertical boreholes in diameters of 88 to 150cm are drilled to depths of 10-12m. These boreholes are filled with concrete, forming the future side walls of the tunnel. Afterwards, the tunnel ceiling is concreted in sections of approx. 13.5m in length directly onto the soil, which serves as lower formwork. The soil is then excavated from within, starting from the future tunnel exits.

The FLIMU® Reinforcing Steel Coupling System was chosen as the most cost effective solution for stabilizing the transition between the drilled piles and the tunnel ceiling because it offsets slightly higher material cost by significantly lower cost of installation labor. In addition, the contractor had already successfully used the FLIMU® System supplied by DSI during the reconstruction at Richard-Strauß Road at the north-eastern section of the Mittlere Ring.

Even in areas with minimal working space, the FLIMU® System provides a simple, trouble free connection, and only three employees are necessary for installation: one employee to operate the lifting vehicle, and two employees to work the extruder. All in all, DSI supplied approx. 35,000 Ø 28mm extruded coupler splices, approx. 20,000 Ø 32mm extruded coupler splices, and the necessary extruding equipment.

Before installation, DSI also carried out tests in original sizes. On-site instructions were given by experienced DSI employees. After the instruction, work could be carried out independently by the construction workers on site.

Supplyrental of equipment

Landeshauptstadt München, Baureferat, Munich, Germany

W&F (Wayss & Freytag Ingenieurbau AG), Munich, Germany; Berger Bau, Berlin, Germany

Baureferat München, HA Tiefbau and HA Ingenieurbau, Munich, Germany

Joint Venture Ingenieurbau LKP,Munich, Germany