Markstein/Nebenwegtunnel

Within the framework of the roughly 100 km long new line between Mannheim and Stuttgart, the topographical conditions east of the town of Vaihingen/Enz called for the construction of the Markstein Tunnel and the Nebenweg Tunnel. The two-track Markstein Tunnel is 2,782 m long. Depending on the type of cross-section, the excavated cross-section fluctuates between 105 and 188 m², the maximum overburden amounts to roughly 67 m. The complete length of the Markstein tunnel passes almost exclusively through layers of Upper Shell Lime. The Nebenweg Tunnel (total length approx. 1,463 m) starts off with a double-track with an excavated cross-section of some 106 m² and then splits up into two single-track tubes with an excavated cross-section of some 65 m². The overcapping rock reaches a maximum of 18 m. The Nebenweg Tunnel is largely located in Letten keuper layers. Both tunnels were built using shotcrete on account of the given rock conditions and the varying cross-sections. In this connection, driving via blasting was mainly executed. A tunnel excavator was used to remove the rock only in the entrance zones and where fault zones with weathered and highly disintegrated rock were encountered. Reinforced shotcrete and rock spikes were principally used to secure the excavated areas. In some places, fore poling lances and support arches were also required. Both tunnels were provided with a watertight inner shell made of reinforced concrete. Joint strips made of synthetic rubber seal the ring-shaped block joints, the horizontal working joints between the base and the vault sections on the other hand, have been fitted with steel plate joint strips. The standard thickness of the inner shell amounts to 35 cm in the single-track tubes, 40 cm in the two-track section and 80 cm in the connecting zones. The "olid track" "System Züblin" was laid in the Markstein Tunnel over a length of 2,400 m. This type of track comprises a jointless bearing plate made of reinforced concrete, in which prefabricated concrete sleepers are concreted into position. The rails are elastically mounted on them. During production, the sleepers are installed with absolute accuracy with the aid of a specially developed laying device making use of vibrations before the concrete of the bearing plate sets. The upper side of the section with the "solid track" system was provided with a sound absorbing layer of foam mortar.

• Country: Germany
• Region: Baden-Württemberg
• Tunnel utilization: Traffic
• Type of utilization: Main-line rail
• Client: Deutsche Bahn AG
• Main construction method: Trenchless
• Type of excavation: Drill-and-blast
• Lining: Shotcrete
• No. of tubes: 1
• Tunnel total length: 2782/1463 m
• Cross-section: 65-160 m²
• Contract Volume: 55/31 mill. DM
• Construction start/end: 1986-1988/89 (34 months)
• Opening: 1988/1989