Rastatt Tunnel

Route

The 4,270-metre-tunnel (2.7 mi) will pass under the whole 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 26.5 metres and they are linked at 500 metre intervals by cross passages. To the north and south are trough structures with a length of 800 or 895 m 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 4.80 metres (15.7 ft) 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 3 to 20 metres (10 to 65 ft). The tunnels will run through sandy-gritty subsoil, mostly under the water table.

The tunnel is the centerpiece of a 17-kilometre-long (11 mi) section of new line, which is designed for operations at 250 km/h. The long-distance passenger services and part of the rail freight traffic passing through the corridor are expected to use it.

Planning

From 1970 to 1983, more than 20 aboveground 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. 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 4,540 m. The northern portal would have been at federal highway 462 and the southern portal would have been near Autobahn 5. In 2002, the tunnel’s planned length was 4,270 m. The northern and southern portals had been moved to the north. In mid-2010, the length of the tunnel was quoted as 4,225 m.

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 1,000 to 500 m 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 12 m between the airlock doors of the cross tunnels. The amended plans provided for a new safety concept over a length of 2,260 m. 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 16 km long northern section of line, which includes the Rastatt Tunnel. The section is designed for operations at up to 250 km/h.

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.

In April 2016, the construction of the tunnel’s connections were put to tender.

Construction

Due to the geological and hydrological environment of the tunnel, a large part of it is being driven by two tunnel boring machines from north to south. Part is being tunnelled through ground that has been stabilised by ground freezing. The planned construction period is six years.

Construction of the project was long delayed until 2013 by a lack of funds, according to the European Commission.

New exploratory drilling for the tunnel began in the district of Niederbühl on 7 April 2011. 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 40 metres by October 2012. Work on the ramp at the northern tunnel portal was tendered in March 2013.

The official groundbreaking ceremony was held on 30 July 2013 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 700-metre-long and up to 29 metre-wide excavation pit was established and approximately 300,000 cubic metres of material and 11,400 square metres 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,

Earthworks for the northern groundwater basin were completed at the end March 2014. Sheet piles were driven into the ground from July 2014 and then further construction started.

The contract for construction of the shell of the tunnel was awarded to Arbeitsgemeinschaft Tunnel Rastatt ("Rastatt tunnel construction community"). The technical leadership was taken by Ed. Züblin AG and the commercial leadership by Hochtief AG. The contract is worth €312 million. It is the biggest contract of the project by value.

The contract for the shell of the tunnel was signed in Berlin on 4 August 2014. 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. Around 3,800 m of the tunnel would be bored, about 470 m 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 tunnel boring machines. The two 90 metre-long and 1,750 t machines would be provided by Herrenknecht AG. The first machine would now be assembled in September 2015 and the excavation would begin in December 2015. The assembly of the second machine would begin in early January 2016 and the excavation would begin in April 2016. With a 10.97 m wide boring shield, each TBM would prepare a usable section of 9.6 m. 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.

According to an updated schedule of June 2015, the beginning of the tunnel drive had been delayed by three months to the spring of 2016 as the first parts of the tunneling machine would be delivered at the end of 2015. The completion of the tunnel shell is still scheduled for July 2018. From the end of 2015, the first parts of the tunnel boring machine were delivered at the north portal at Ötigheim and were assembled there in preparation for driving the eastern tube from early February.

The first tunnel boring machine was symbolically launched on 8 December 2015. It was expected to start driving the eastern tunnel at the end of May 2016.

A stretch of earthworks with a length of about 7.5 km was completed to the north of the tunnel at the end of 2006 and it has been extended at Ötigheim since early 2013.

Costs

The project costs of around €693 million for the route including the tunnel are to be provided by the federal government.