Light Rail Bochum Lot F1

Construction lot F 1 in the centre of Bochum was built as part of the U 21 (Bochum-Gelsenkirchen) urban railway line. The lot comprised 2 one-track running tunnels constructed by mining means using shotcrete with a total length of 1,276 m, Lohring Station and a 110 m long ramp. The station is one of the first in Germany to be built without pillars so that visibility is not obscured. The two 20 and 60 m long station grids and the ramp were constructed via cut-and-cover, the 95 m long station hall at Lohring by mining means in accordance with a special proposal from the consortium. The individual tunnels were driven from a 20.20 m deep starting shaft, lined with shotcrete, which was sunk in advance. The rock was loosened by means of a road header with a 1.50 m long advance rate. The up to 18 m deep construction trenches for the two station grids constructed by cut -and-cover were secured by a lining of driven girders. The successive excavation and installation of anchors as well as the creation of the structures in reinforced concrete took place beneath steel ancillary bridges where roads were present. The 95 m long station hall with an excavated cross-section of 200 to 225 m² was headed by mining means. Owing to the geology, geometry, the slight overburden of minimally 3.80 m beneath a busy road and the neighbouring built-up area, the station was constructed in part-cross-sections with advance side walls. The core crown section with a length of 12 m was also split up into a number of part excavations. The rate of advance amounted to 1.0 m. The outer shell comprised 28 cm shotcrete with two-layer reinforcement and support arches TH 21 and TH 13. Shotcrete early strengths of 20 N/mm² after 12 h were required for heading the station hall. Thanks to a special recipe and a non-alkaline setting accelerator, it was possible to safely achieve this goal. The station hall drive was monitored by a far-reaching measurement programme. After concluding the drive, the maximum Settlements amounted to only 58 mm. The inner shell of the station comprising watertight reinforced concrete B35 has a wall thickness of 60 cm and the base is 2 m thick. Specially constructed formwork systems in the form of hydraulically mobile steel constructions were used for the walls and roof vaults of the inner shell.

Country: Germany
Region: Nordrhein-Westfalen
Tunnel utilization: Traffic
Type of utilization: Underground, urban and rapid transit
Client: Stadt Bochum, Tiefbauamt
Contractor: Bilfinger + Berger Bau AG, Philipp Holzmann AG, Dyckerhoff & Widmann AG, Beton- und Monierbau GmbH, Thyssen Schachtbau GmbH
Main construction method: Trenchless
Type of excavation: Roadheader
Lining: Concrete formwork
No. of tubes: 2
Tunnel total length: 954 m (incl. 1 station)
Cross-section: Single tubes: from 32 to 41 m²; Station Lohring: from 200 to 225 m²
Contract Volume: approx. 95.5 mill. DM
Construction start/end: April1993 till May 1997