Leipzig City Tunnel

The tunnel is used by 6 out of 7 S-Bahn Mitteldeutschland lines. It is hoped that shorter intervals and faster connections will allow public transport to carry more passengers and thereby relieve road traffic in the city. In addition, it will bring more passengers directly by rail from Leipzig Hauptbahnhof to the city centre and convert the terminus to a partial through-station.

Additionally, it was planned to run one intercity train per hour in each direction through the tunnel. However, until December 2012 the electrified route ended in Reichenbach im Vogtland. Therefore, the states of Saxony and Bavaria, the Federal Government and DB were planning to continue rail electrification first to Hof, and later on to Regensburg and Nuremberg. The section to Hof was fully electrified by 15 December 2013.

Early in 2002, the Saxony State Government gave support for the implementation of the City Tunnel.[3] On 18 March 2003, they approved the project formally.[5]

On 6 January 2010 a correction notice to the tender for the Leipzig train network was issued, announcing that the start of the new train service would be delayed for another year until the timetable change in December 2013.[6]

The 2002 framework agreement foresaw the total project cost as €571.62 million, financed by funds from the State of Saxony (€182.02 million), by the European Union (ERDF programme, €168.73 million), the Federal Government (€191.73 million), Deutsche Bahn (€16.36 million) and the City of Leipzig (€12.78 million).[7] This agreement covered many issues, including the refurbishment of the stations and the electrification of several sections.[5]

At the end of 2001 it was expected that the total cost would amount to 1.04 billion DM. DM 240 million would come from the EU Structural Fund. Additional safety measures led to increased costs.[8]

In 2006, the ERDF funding allocated at the end of the funding period was reduced from 168.73 to 127.59. million Euro, which was spent in its entirety. For the 2007-2013 funding period, a further follow-up funding application was submitted, but was not approved (February 2011).[9]

The contractor's representatives DEGES expected the costs in December 2006 to amount to 585 million euro. A risk analysis by Deutsche Bahn saw at that time possible additional costs of up to 73 million euro.[10] In December 2007, the additional cost was estimated at 133 million euro, so that the expected total cost will be 705 million €.[11]

After the estimated total costs had risen by the end of November 2009 to 893 million euro, the state auditors of Saxony reviewed the project. At the end of February 2010, a further cost increase to 960 million Euros was announced.[12] According to the State of Saxony, this remains the expected total cost (as of September 2010).[7]

The federal share provided is limited, in line with the framework agreement, to 191.73 million euro (plus wage and price increases). With the exception of the indexation component, the federal share has already been used in full (as of September 2010). The additional costs are mainly supported by the Free State of Saxony and the City of Leipzig, and to a lesser extent, the German Railways.[7]

The project has been criticised by various parties because of the high construction costs for the relatively lightly-used Leipzig S-Bahn, for the limited usability by long-distance trains and for the long-lasting construction work in the city centre, with its associated obstruction and loss of revenue.

North portal of the unfinished tunnel of 1915 (in 2010)

When constructing Leipzig Hauptbahnhof, the Saxon State Railway had planned a tunnel to Bayerischer Bahnhof. In 1913 and 1915, a 710m long section below tracks 22 and 23 was created before the work came to a halt due to World War I and a lack of funds. As part of the modernisation of the railway station, this tunnel section was excavated in 1997 and demolished within the station hall area.[13]

In the early 1990s the plans for a public transport tunnel through central Leipzig, which had existed for decades, were presented together with the results of new planning in 1995. In 1996 the DB and the Land of Saxony, expressed their support for the project. In the same year the Land, City Planning and DB AG Company founded the planning company S-Bahn Tunnel Leipzig GmbH.[8] Following a cost-benefit analysis in 1998, a planning application was issued. In 2000 planning approval was granted.

In the autumn of 2001, Saxony invited DB to be the owner of the City Tunnel project. The company was therefore expected to build the tunnel on its own financial risk.[8] After the completion of a financing agreement in the spring of 2002[14] the invitation of the individual building sub-contracts took place.

On 9 July 2003, the construction began with the official groundbreaking. At the start of the construction process, the tunnel was planned to be in operation by late 2009.[15] Initial activities mainly consisted of ground investigations and the relocation of services. The construction of the underground stations began in early 2005.

At the end of March 2005 preparations for building the platform area of the main station began. This space was created for the following excavation.[1] In December 2006, the construction of the ramps at the main station was interrupted after cracks were found in neighbouring station buildings.[16] Between 17 February and 25 March 2007 two auxiliary bridges of 105 m were built as part of the construction in the Central Station. In addition 1,400 metres of track and eight sets of points were rebuilt.[17]

Unfitted-out tunnel (in 2008)

On 11 January 2007 the tunnel boring machine called Leonie began (with a ceremony at the Bayerischer Bahnhof) to symbolically bore the first tunnel. The tunnel's godmother is Angelika Meeth-Milbradt, wife of then Prime Minister of Saxony Georg Milbradt[18] The excavation began on 15 January 2007 and on 10 March 2008 reached the railway station, so completing the first bore.[19] After the return of the tunnel boring machine to Bayerischer Bahnhof in late March 2008, the excavation began of the second bore on 9 May 2008.[20] On 31 October 2008, the tunnel boring of the tunnel ended with the completion of the second bore.

Ahead of the expected opening in December 2013, activities centred on the interior fitting-out of the tunnel and railway stations. In mid-February 2009, the contract to develop the five stations was advertised throughout Europe. The contract ran from February 2010 to November 2011.[21] The tender has been divided between two companies.[22]

Construction at Marktplatz in February 2006

Entrance of Markt station

Trains of S-Bahn Mitteldeutschland at Markt station

In order to prevent settlement of more than 30 millimeters at the tunnel grout shafts have been built. Of these, were generated as necessary, heave of the soil by high-pressure injections. Partially, the soil was already previously raised by a few millimetres in order to reduce the final setting depth. Under the Petersstrasse an about 250 m long supply tunnel from GDR times was used for the injection. It begins and ends at St. Peter's bow on the market. All the buildings in Petersstrasse can be achieved. Of the Verpressschächten holes were made, terminating at the buildings. These holes are provided as needed and then with Verpressrohren Verpressgut is introduced under high pressure. The Verpressgut is composed of binder and water.

Here, the Compensations-grouting process was applied. For it are in different places pits, the so-called CGV-shafts arranged. Overall, the method consists of four phases. First, dug wells or pits at appropriate points, be created from which horizontal wells. This can be, according to a length of up to 70 m. In the horizontal drilling valve tubes are installed. Through these tubes is finally pressed cement into the ground. This will start the actual backup of the building. The soil is compacted and any gaps there may be filled.

In a second phase, the land in some places is controlled by additional increased pumping. The elevation is to compensate for reductions occurring under certain circumstances during the tunneling. At the time the bore of the City Tunnel tubes the buildings in the vicinity of the bore be monitored. With precise technique smallest movements are registered. Accurate to 0.25 mm, the units can monitor the structural elements of buildings. For the case that the uplift not the actually occurring reduction can compensate, further cement is pressed into the ground and kept the buildings at a constant level.

Even after the completion of the excavation, the houses are still monitored regularly and, if carried further injections.