Light Rail Stuttgart, Line connecting recreation area Waldau, construction lot SF 1 and SF 2

The urban rail tunnel from the Altenbergstaffel to the Ruhbank is the first part of the 11.8 km long south-eastern section of the valley-crossing line via Sillenbuch to Ostfildern. The sport and recreational facilities at Waldau are also linked up with the urban rail network by means of this new route. The Lot SF 1 branches off from the existing, operational tunnel "Neue Weinsteige" and runs in a wide arc to the Waldau Sports Centre at a depth of up to 50 m, where it reaches the Waldau stop, which was built by cut-and-cover. The gradient here amounts to as much as 7%. The main tunnel comprises a two-track tube with a length of 1,064 m and 2 single-track tubes with a total length of 465 m. The excavated cross-sections amount to 38 m² in the single-track, 68 m² in the two-track section as well as up to 210 m² in the enlargement zone. In order to head the tunnel, far-ranging slope securing measures had to be undertaken at the Wernhaldeklinge - on account of extremely constricted conditions - in order to accommodate the construction site and the tunnel access. From this point, a 58 m long escape tunnel was driven, via which all operations for the main tunnel were executed (muck removal, supplying the shotcrete, supporting aids, inner shell concrete, steel, etc.). The entire tunnel was driven by the shotcreting method, with the outer shell attaining a thickness of from 20 to 35 cm. ln geologically tricky sections as well as in the zone where the existing urban railway and buildings had to be undercut, the ground was improved in advance through grouting. The inner shell thickness is 35 to 80 cm thick depending on the site of the cross-section and is executed in watertight concrete. The 722 m long urban railway tunnel in Lot SF 2 created by cut-and-cover, which runs directly under the Georgiiweg, passes beneath the Mittlere Filderstrasse and then links up with the existing railway track in the direction of Sillenbuch, joins up with the Waldau Tunnel, which was driven by mining means. The 2 stops "Waldau" and "Ruhbank" are also located in this section, between which the tunnel is widened to accommodate 3 urban railway tracks, with the central track serving to house 5 urban railway trains on stand-by. Before the up to 14 m deep excavation comprising back-supported sheet piling walls was created, a large number of supply and disposal lines had to be laid, some provisionally. The tunnel made of watertight concrete, which was created without a working room, possesses a rectangular cross-section with a clear width of up to 14 m given up to 1.10 m base and slab thickness and 85 cm for the walls.

Country: Germany
Region: Baden-Württemberg
Tunnel utilization: Traffic
Type of utilization: Underground, urban and rapid transit
Client: Landeshauptstadt Stuttgart/Stuttgarter Straßenbahnen AG
Main construction method: Trenchless
Type of excavation: Drill & blast
Lining: Concrete formwork
No. of tubes: 1 (single and double track profile)
Tunnel total length: 2251 m
Cross-section: mining means 38 to 210 m²
Contract Volume: approx. 188 mill. DM
Construction start/end: 1993 till 1997