Metro Munich, Line U1 West, construction lot 6 - Station Westfriedhof with depot and P+R facilities

The construction lot comprises the creation of the approx. 220 m long station as well as the roughly 340 m long adjoining 3-track loop and siding rails with the P-R underground parking facility situated above them. The structure ranges up to 15 m down from the surface and was built by the slotted-wall /top cover method. In the process, it is located in the upper groundwater storey to a depth of approx. 11 m. At the centre of the lot, there is no continuous retaining zone between the quaternary gravel and the tertiary sand. Instead of placing the slotted walls down to a depth of 31 m in the retaining zone below the tertiary sands in order to form a compact trough, a special proposal was accepted which foresaw ending the slotted wall in the tertiary sand in order to create an immersed wall with water flowing below it. The 1.20 m thick and up to 23 m deep slotted walls serve to secure the excavation and are subsequently used as the final structural wall. After lowering the groundwater level within the structure, the 2 supply ramps were created. The further elements such as bases, supports, walls and intermediate ceilings were erected by excavating from the bottom to the top. Until the mid-80s, slotted walls were employed in the construction of the Munich Underground on a number of occasions, however, grab dredgers, which were customary for the time, were used. Later, slotted walls gave way to the bored pile version. In this construction section, cutting technology using a Bauer BC 30 cutter was made use of for the first time. The creation of slots by means of a cutter distinguishes itself - compared with grab dredging technique- through higher performance, reliability, accuracy and above all, better environmental compatibility. The cutter operates almost silently and vibration-free even given solid rock layers.

• Country: Germany
• Region: Bayern
• Tunnel utilization: Traffic
• Type of utilization: Underground, urban and rapid transit
• Client: Landeshauptstadt München, U-Bahn-Referat
• Consulting Engineer: Cronauer Beratung Planung
• Contractor: Hochtief AG, Wayss & Freytag AG
• Main construction method: Open
• Type of excavation: Cut-and-cover
• No. of tubes: 1
• Length: 560 m
• Contract Volume: 64 mill. DM
• Opening: 1996