Stadtbahn zum Killesberg

Through the urban railway link “Zum Killesberg", a fast and comfortable rail connection between the central transfer point Hauptbahnhof and the Killesberg with its park facilities, fairgrounds and surrounding residential areas. Travelling time is only 5 min. The new route can be split up into three part sections:

• the open section
• the tunnel section
• the Killesberg Messe station.

The open section - sodded track - branches off from the urban railway line at the Heilbronner Straße and reaches the tunnel section after an approx. 7 % climb after about 430 m - mainly through a cutting (steep walls made of cut stone). The core of the urban railway line is the 360 m long tunnel. The First 70 m was completed by cut–and-cover. With an overburden of 6-14 m. the upper layers of gypsum keuper and schilf sandstone were penetrated, whereby as from approx. tunnel metre 200 until the end of the tunnel, the roof and the upper part of the walls were located in a zone with old quarry fill. The composition of the quarry fill material was extremely heterogeneous comprising sandstone blocks of varying sizes with edge lengths of up to 80 cm. In some cases, pure sandstone waste. Following a comparative evaluation of various construction methods, there was a clear decision in favour of the shotcreting method. The bench and base were completed behind the advance crown drive. On account of the major cross-section at the end of the enlargement section (17.8 m wide), the walls were driven until the station was reached. In order to avoid settlements caused by tunnelling Operations in the vicinity of the Art Academy, a screen of horizontal props (approx. 11 m set at 30-35 cm gaps), created with the aid of high-pressure grouting (HDI screen), which is incorporated laterally in the schilf sandstone, was installed as an additional means of advance support in the crown zone. Prior to this, conventional injections designed to fill up the cavities in the quarry waste were carried out. After the completion of the HDl screen, the actual tunnel drive was launched. The calculated deformations of approx. 4 mm corresponded well with those actually measured. No damage was caused. In order to drive the enlargement section before the station, various special measures were undertaken. Systematic, advance cavity grouting and securing of the roof with injection lances accompanied driving. The entire crown zone in the quarry fill area was systematically grouted in advance using up to 6 m long injection lances. All in all, the Killesberg Tunnel could be completed safely and successfully by means of the chosen support and securing methods in spite of the tricky geological conditions that prevailed - partly in a filled quarry zone. The approx. 120 m urban railway station was completed via cut-and-cover.

• 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: Roadheader
• Lining: In-situ concrete formwork
• No. of tubes: 1
• Tunnel total length: 360 m
• Cross-section: ca. 80 m²
• Contract Volume: 74 mill. DM, Tunnel 20 mill. DM
• Construction start/end: 1990-1993 (3 years)
• Opening: April 1993