The Rastatt Tunnel is a railway tunnel that is currently under construction on the Karlsruhe–Basel high-speed railway under Rastatt in the German state of Baden-Württemberg. Once complete, the line will be used by long-distance passenger services and freight. It will form part of the Rotterdam–Genoa corridor; the tunnel is also part of the Main line for Europe project between Paris and both Bratislava and Budapest.
Having been under consideration since the 1970s, and given planning approval during 1996, the tunnel's construction was delayed by decades due to a lack of financing. During 2013, construction finally commenced with the awarding of a contract to Arbeitsgemeinschaft Tunnel Rastatt ("Rastatt tunnel construction community"). In 2012, it was projected that Rastatt Tunnel should be opened during 2022. Being financed by the German federal government, early projections forecast a total cost of around €693 million.
On 12 August 2017, there was a collapse during the construction of the tunnel's eastern bore. This collapse not only affected the tunnel, but also stopped operations on the Rhine Valley Railway, disrupting international rail traffic; the line was not reopened until on 2 October 2017. While construction work on the unaffected western bore was resumed during September 2017, the eastern bore was intentionally sealed with concrete as a measure to stabilise the ground. The project was re-planned to account for the collapse; as of August 2019, the eastern bore is intended to be dug out using traditional cut-and-cover construction methods. The Rhine Valley Railway will also be relocated during the renewed construction phase to minimise the potential impact of further instability. Tunnelling was completed in August 2025, with the tunnel planned to come into service by the end of 2026.
Route
The will pass under the entire Rastatt urban area, the existing Rhine Valley Railway and the Federbach flats. It is the largest tunnel in terms of cross-section to be built on the high-speed line and begins east of Ötigheim and ends at Niederbühl. The distance between the track-centres of the two single-track tunnels is and they are linked at intervals by cross passages. To the north and south are trough structures with a length of connecting to the rail tracks on the surface.
The gradient descends from both portals towards the centre of the tunnel. The two tracks are largely in circular tunnels with an inner radius of in sections with an open design a rectangular cross-section has been chosen with an equivalent cross-sectional area.
The planned cover of the tunnels is between . The tunnels will run through sandy-gritty subsoil, mostly under the water table. The tunnel is the centerpiece of a section of new line, which is designed for operations at . The long-distance passenger services and part of the rail freight traffic passing through the corridor are expected to use it.
The local geology largely comprises sedimentary rock, while various underground rivers are also present in the vicinity; the Rhine itself is roughly seven kilometres west of Rastatt. It has been observed that there is a high presence of ground water around the tunnel's route, which is particularly concentrated around the sandy sediments found up to 10 metres below surface level.
History
Planning
Between 1970 and 1983, more than 20 above ground options for section 1, to which the tunnel belongs, were considered. Under planning procedures introduced in 1983, five main above or underground options in the area Rastatt with different design speeds were examined. In its spatial planning assessment, the administration of the Karlsruhe region called on Deutsche Bundesbahn to discard the aboveground options and to provide for a tunnel under Rastatt. As there is mainly rail-freight operating on the line and to achieve permissible noise levels for the local residents and avoid noise mitigation at the vehicles and tracks a tunnel was planned in the sandy plains of the Rhine valley. Also to avoid construction noise a construction in mining technique was foreseen instead of cut and cover what would be much simpler in this environment. The initially planned route of the new line through Durmersheim, Bietigheim and Ötigheim was fought intensely by local residents. Under political pressure, the new route was eventually moved to follow the already planned deviation of federal highway 36. According to Deutsche Bahn (DB), this transfer was possible at no additional cost, taking into account the need to resolve local issues if the previously considered route was chosen. According to DB, the selected tunnel solution is more economical, has greater capacity, would allow more efficient operations and would allow shorter journey times. As a result, the regional planning process was launched in July 1986 with the proposed route following the proposed new federal highway closely and then passing through a tunnel. In the middle of 1987, Deutsche Bundesbahn intended to initiate the planning approval process in late 1987. The B36 bypass was built between 2002 and 2004.
The planning process for section 1 was launched on 27 June 1990. Due to the high cost of the tunnel solution, possible savings were investigated in 1991 and 1992, including other routes for the tunnel and a shorter tunnel. The planning approval procedure was completed on 19 March 1996. After several complaints were dismissed, the decision on section 1.2, to which the tunnel belongs, was finalised on 11 August 1998.
In the spring of 1997, the Federal Ministry of Transport commissioned Deutsche Bahn to carry out a study comparing an aboveground route with the underground route. The result was verified by the Federal Railway Authority (Eisenbahn-Bundesamt) and notified to the Baden-Württemberg state government in December 1997. The study confirmed that, an aboveground route would have a similar cost as a tunnel, but it would not provide the same increase in capacity.
In 2000, the planned tunnel would have had a length of . The northern portal would have been at federal highway 462 and the southern portal would have been near Autobahn 5. (map with status of September 2000) In 2002, the tunnel's planned length was . The northern and southern portals had been moved to the north. (map with status of May 2002) In mid-2010, the length of the tunnel was quoted as .
In early 2009, it was intended to revise the planning for the Rastatt Tunnel, which was now over ten years old and to begin construction in early 2011. Both would be financed from funds from the economic stimulus package II. Because of the high financial requirements and the long duration of the project, it was later separated from the stimulus package. In 2011, Deutsche Bahn proposed an amendment to the plan, with among other things, the longitudinal spacing of the cross tunnels reduced from and special construction methods in the portal area to deal with tunnel boom. Among other things, the route of the eastern tunnel was shifted slightly to give a uniform distance of between the airlock doors of the cross tunnels. The amended plans provided for a new safety concept over a length of . The amendment was approved in November 2012. According to a media report the amendments to the plan were necessary because of new safety regulations (as of February 2012).
On 24 August 2012, the Federal Ministry of Transport, Building and Urban Development concluded a financing agreement on the northernmost section of the Rhine Valley Railway. It includes a northern section of line, which includes the Rastatt Tunnel. The section is designed for operations at up to . At the end of February 2012, a notice was published on the tendering of the construction contract for zoning section 1, to which the tunnel belongs. The estimated contract value was €808 million. Tendering and contracting were to run from May 2013 to August 2014.
Construction
During 2001, the construction interval was forecast to take around six years to complete. However, prior to any work commencing, the construction phase of the project was subject to multiple postponements; according to the European Commission, these delays were due to a lack of available funds.
On 7 April 2011, fresh exploratory drilling for the tunnel began in the district of Niederbühl. Another exploration program began between Ötigheim and Rastatt Süd on 9 May 2012. Three rigs were due to drive 40 holes to depths of up to by October 2012. Work on the ramp at the northern tunnel portal was tendered in March 2013.
On 30 July 2013, the official ground-breaking ceremony was held at the future groundwater basin under Autobahn 5 in Niederbühl. This was to allow construction work to commence between Basheide junction and Rastatt Süd. The work was expected to be completed by 2015. At the end of 2013, work began on the construction of the northern groundwater basin. As part of works worth about €13 million, a and up to excavation pit was established and approximately of material and of sheet piles were installed. The work was expected to be completed by October 2014 (as of late 2013). It was expected that the construction of the actual groundwater basin would begin in early 2015, By the end of March 2014, the earthworks for the northern groundwater basin has been completed. Starting in July 2014, sheet piles were driven into the ground in preparation of further construction activity commencing.
The contract for construction of the shell of the tunnel was awarded to Arbeitsgemeinschaft Tunnel Rastatt ("Rastatt tunnel construction community"), a company founded specifically to undertake this project. The technical leadership was taken by Ed. Züblin AG and the commercial leadership by Hochtief AG. The tunnel contract is worth €312 million; making it the biggest contract of the project in terms of value. On 4 August 2014, the contract for the shell of the tunnel was signed in Berlin. Construction work was expected to start in November 2014 with the preparation of a building site area in Ötigheim. The first tunneling machine was expected to be assembled in April 2015 and the driving of the tunnel was expected to start in October 2015. The completion of the shell was intended to be achieved at the end of the first quarter of 2018. The completion of technical construction is to follow in 2020 and trial operations are scheduled to start in 2022.
Due to the geological and hydrological environment of the tunnel, a large part of it is being driven by two tunnel boring machines (TBMs), which travelled its length along the north-to-south alignment. Some of its length was tunnelled through ground that has been stabilised by a combination of ground freezing (using either brine or liquid nitrogen) and concrete injections. Around of the tunnel would be bored, about would be built using the New Austrian Tunnelling method or by cut-and-cover.
In early December 2014, Deutsche Bahn provided updated details of the procurement of the two TBMs. The two and machines would be provided by Herrenknecht AG. At the time, the first machine was to be assembled in September 2015 and excavation work was set to commence during December 2015. The assembly of the second machine would begin in early January 2016 and the excavation would begin in April 2016. With a boring shield, each TBM would prepare a usable section of . The contract for the two machines was estimated to be worth €36 million. The structure of the tunnel was still estimated to be completed in the first quarter of 2018.