Fast and direct: The Leipzig city tunnel

1. Project

The Leipzig city tunnel is the final and central component of the railway system restructuring process in Greater Leipzig. The completion of the tunnel will not only bring improvements to the suburban train system - transport between the region and the city will also be improved, and the tunnel will give a major impetus to the development of the city’s transport system.

The tunnel provides a direct rail link between the area to the south of the city and the central station in the northern part of the city centre. Until now, trains travelling along the north-south axis have had to circumvent the city centre - a time-consuming process. In future, they will simply travel underneath it.

In this way the Leipzig city tunnel will make regional rail traffic faster, more efficient and more convenient for passengers across the board: The fast north-south axis below Leipzig city centre will reduce total travel time by as much as 40 minutes on some routes.

The city tunnel is the fast transport hub for central Germany: The S-Bahn urban railway network for the Central German region is the new backbone of S-Bahn and regional rail transport in the Leipzig/Halle conurbation. As of late 2013, six new S-Bahn urban railway lines will link the business region around Halle and Leipzig with the surrounding area faster and more efficiently, ensuring much shorter journey times by rail. The benefits will be felt by the entire region – economically, environmentally and in terms of a better quality of life.

The Leipzig city tunnel has two 1.438 km long tunnels, one in each direction, and four underground stations – Bayerischer Bahnhof, Wilhelm-Leuschner-Platz, Markt and Hauptbahnhof (Central Station). The shells of the tunnel and the stations have already been completed, work is currently in progress on fitting out the interiors of the four stations and preparing the tunnels for the trains.

Following the completion of a trial phase, the city tunnel will open for operation when the new timetable comes into effect in December 2013.

1.1 The features of the stations

The four underground stations have been designed by well-known architects to be both functional and aesthetically pleasing. Following completion of the building shells, each station is now being given an individual appearance adapted to its location and function. The interior fitting out of the stations will take place in three phases.

Hauptbahnhof | Central station

The platform, 215 metres in length, lies beneath the western area of the central train station and is approached via glass atria. The ‘main atrium’ links the underground station with the upper train station via stairs and elevators to make changing between the two easy and convenient. The glass atrium within the station concourse gives the station interior a light, transparent look; daylight is supplemented by modern lighting elements. The ‘small atrium’ is located outside the station building below the forecourt and leads through pedestrian tunnels to the LVB tram stops and into the city centre. The solid wall areas of the underground station are made of natural stone, the ceilings of sheet steel and aluminium, the parapets of steel and glass.

Markt

Welcome to the inner city! In the future, S-Bahn trains and regional trains will stop directly beneath the market square, at a depth of 22 metres. Two entrances – one in the north and one in the south of the market square – lead to the modern concourse with its 140-metre-long island platform. The side walls have a facade of terracotta slabs; the facades of the front and rear station walls and the service rooms on the platform are made of ceramic rods. The south entrance to the Markt station is the original entrance to the former underground exhibition hall dating from 1925. When construction work began, the solid stone blocks with their attractive Art Deco decorations were completely removed and then restored by experts. They are now being integrated into the entrance of the new station.

Wilhelm-Leuschner-Platz

This station stretches on a north/south axis beneath Martin-Luther-Ring to the middle of Wilhelm-Leuschner Platz, at the junction with Markthallenstrasse. The island platform, 140 metres in length, lies some 20 metres below the surface. The main feature of the station interior is the glass brick elements which are lit from behind to give the impression of daylight. The two entrances are located at either end of the station where escalators and stairs are provided. The platform can also be reached by elevator from the northern entrance, at the southern end of Peterstrasse.

Bayerischer Bahnhof

The station’s architecture is a unique blend of historical and new building elements. Generous lightwells allow daylight to penetrate down to 20 metres below ground, to the 140-metre-long island platform. The walls behind the tracks will be clad with large, silver-coloured aluminium sheets. Integrated into these sheets is an interactive strip of coloured light which runs the entire length of the platform at eye level and shows changing colours. The restrained design of the station entrances blends harmoniously with the historical buildings. The new station makes Bayerischer Platz into a major traffic hub in the south of Leipzig. The main entrance is located in front of the famous Portico; the smaller southern entrance is inside the former station concourse.

1.2 Equipping the city tunnel for rail traffic

In the course of work to prepare the city tunnel for rail traffic, the shell of the tunnel will be transformed into a complete section of underground railway. This involves providing rail tracks and overhead lines in both tunnels and in the adjacent areas; signal technology, drainage systems and an electrical power supply will also be installed. Work began in 2009 and will continue until summer 2013. Trial operations will then run until December 2013.

Track-laying was completed in mid-2011. Unlike conventional railway tracks, the Leipzig city tunnel uses ‘slab tracks’. The tracks are not laid on a ballast bed but are mounted on concrete which, in combination with single rail supports made of neoprene, provides a mass spring system the aim of which is to absorb the vibrations of the trains and reduce their transfer to the buildings above the tunnel.

The entire tunnel will be provided with an overhead line designed specially for railway tunnels. A conductor rail will supply the trains with electricity as they travel through the tunnel. New overhead line systems will also have to be installed in the northern and southern entrances to and exits from the tunnel. More than 80 new pylons were required to supply power for the southern connection alone.

A complex system of railway control and command technology must be installed in order to ensure the smooth operation of rail traffic in the tunnel. The control and monitoring of the more than 100 signals and 50 switches in the city tunnel required the laying of some 100 kilometres of cable.

In addition to this, drainage pipes and fire-fighting systems also had to be installed. Low and medium voltage systems with five transformer stations were installed to supply power for the southern track connection and the tunnel with its four stations. The tunnel will also be equipped with an extensive telephone system.

1.3 Additional construction work to integrate the city tunnel into the existing infrastructure

The Leipzig city tunnel will be integrated into the existing rail network north of the central station (Hauptbahnhof) and south of Bayerischer Bahnhof. This task was particularly complicated in the north, where there is a close network of tracks with high train frequency. Most of the construction work is taking place while operations continue.

Construction work in the north of Leipzig
The construction of the city tunnel has necessitated extensive alterations to the infrastructure around the station. Two major elements of these flanking measures are the new overpass at the western ramp of the city tunnel (in the area of the former Magdeburg-Thüringer station) and the new Leipzig Nord station.

The overpass at the western ramp of the Leipzig city tunnel (in the area of the former Magdeburg-Thüringer station) will make it possible for trains to cross on two levels at speeds of up to 80 km/h. This will allow trains to enter and leave the tunnel simultaneously. The tracks at the western ramp will lead across the overpass between tracks crossing on the same level. Measures to integrate the construction included the building of some 5,500 square metres of retaining wall. Following the completion of the infill of this area of the ramp construction, work on developing a track diagram to Platform 6 of Central Station began in 2010. 

The new Leipzig Nord station integrates traffic flows at the northern ramp of Central Station into the new concept. Trains entering and leaving the tunnel meet here close to Central Station. Main tracks leading to the north ramp are to be created in the vicinity of the new station from the two tracks to Bitterfeld (6411) and the track to Eilenburg (6360). This concentration of trains entering and leaving the tunnel allows them also to travel at 80 km/h. Construction work on the new station was completed in autumn 2010.

Construction work in the south of Leipzig
The future operation of the city tunnel (CTL) requires complex changes to the Engelsdorf – Gaschwitz section of the line. Rail operator Deutsche Bahn AG is modernising some 25 kilometres of track and 21 switches here. New retaining walls and noise protection walls will be built and a new station, Markkleeberg Nord, will be created. Other stations will be completely rebuilt and modernised, four railway bridges in Markkleeberg and Leipzig will be fully renovated. Most of this work comes under the heading of ‘supplementary network measures’, whose aim is to redesign the southern approach tracks for the CTL and to adapt track systems and stations along the line to the altered route.

Between July and the end of September 2010, DB completely electrified the 18-kilometre-long stretch of track between Borna and Geithain at a cost of some eight million euro. The aim of this project was to integrate the town of Geithain and the stations along that section of the line into the electrically-powered Central German S-Bahn network of the future and to extend the range of the local train service via Borna further northwards through the city tunnel. A total of some 300 pylons were erected along the single track line at intervals of 60 metres for this. Pylons with two crossbeams, covering both tracks, were provided for the only double-track section – in the station at Frohburg. The pylons have been carrying high voltage lines since October 1st.

2. Benefits

2.1 The new network will be of benefit to many:

Many commuters who work in Leipzig and live in the surrounding area will be able to travel to the city much more quickly than previously and will often reach their destination direct thanks to the four inner-city stations in the city tunnel.

People living in the region will be able to travel more easily and conveniently to Leipzig – for a shopping trip, to eat out or to attend a cultural event. The entire inner city will profit from this - from retail outlets to theatres.

City dwellers will be able to reach the leisure and recreational areas outside the city much more quickly and reliably than in the past. This will be a major benefit to the towns and villages in the region; they can look forward to seeing many more visitors in the future.

Many of those visiting Leipzig from further away will also find it easier to reach their destination, whether it be the Leipzig Fair, the ARENA Leipzig, the Red Bull Arena or one of the many other highly attractive sites the city has to offer.

2.2 The new network is more environmentally-friendly

Thanks to the new, much more attractive connections to the entire region, the Leipzig city tunnel will convince many more people to take the train in future. This could mean that some 42.7 million fewer kilometres are driven by car every year. And this would reduce the burden on the climate by 10,000 t. of CO2 annually while also reducing fine dust pollution in the city of Leipzig by two tonnes.

The volume of CO2 saved alone is roughly equivalent to the annual emission of 200 average households in Germany. And congestion on Leipzig’s streets will improve because there will be less traffic in future.

The trains which will use the city tunnel in future will meet the highest technological requirements. They are electric multiple units of the Talent 2 series from Bombardier Transportation which can travel at speeds of up to 160 km/h; they are air-conditioned and extremely environment-friendly.

3. Financing plans

  • Project partners: Free State of Saxony & Deutsche Bahn AG
  • Total costs: EUR 960,00 million (status 02/2012)

Sources of financing:

  • Free State of Saxony/City of Leipzig: EUR 194.8 million
  • European Union (EFRE): EUR 168.73 million
  • German government pursuant: EUR 114,53 million
  • German federal government,
    in acc. with sect. 8, par. 1 and 2 of the Bundesschienenwegausbaugesetz
    (Federal Railway Infrastructure Development Act): EUR 114.53 million
  • German federal government in acc. with the
    Gemeindeverkehrsfinanzierungsgesetz
    (Community Transport Financing Act): EUR 77.20 million 
  • Deutsche Bahn AG: EUR 16.36 million

4. Facts and Figures

4.1 Technical project data

  • The City Tunnel consists of two single-track tunnel tubes constructed using shield driving 
  • Length of each tunnel tube 1,438 m 
  • Total length of project approx. 5.3 km 
  • Tunnel length including stations and ramps approx. 4.0 km
  • Construction of three ramp structures, open cut method (two ramps at Hauptbahnhof, one at Bayerischer Bahnhof)
  • Excavated cross section 9.0 m
  • Internal tunnel tube diameter 7.9 m
  • Top edge of tunnel runs between 8 m and 16 m below ground
  • The excavated cross section will be supported during shield driving by tubbing segments with a wall thickness of 40 cm
  • A tubbing segment consists of 7 stones and a capstone, and weighs about 47 mt
  • Over 13,000 tubbing segments will be inserted
  • The railway bed in the tunnel will be built as a slab track. For sound absorption in the inner city area a spring-mass system will be installed
  • The contact wire will be designed as a conductor rail
  • A conventional signalling system will provide for operational safety

4.2 Tunnelling

  • The tunnel boring machine (TBM) has been designed and tailored to the specific needs of the city tunnel and the local soil conditions
  • The shield diameter is 9.0 m
  • The total weight of the TBM is 1,100 mt
  • Including the trailing section, the TBM has a length of 65 m
  • The TBM has a total connected load of 2.5 MW
  • The TBM is driven by 14 pairs of presses. Their maximum pressing power is 65 MN
  • The integrated stone crusher is capable of crushing stones up to 80 cm edge length
  • To pre-explore the ground, the TBM has been provided with a special seismic system capable of recognising any anomalies or boundaries of a bed 40 m in advance

4.3 The Cutter

Leonie::Tunnel boring machine
Tunnel boring machine 'Leonie'
  • The cutter has been designed as a partially open hydroshield 9.0 m in diameter
  • The cutter weighs approx. 100 mt
  • It is driven by eight motors with a total capacity of 880 kW
  • Wheel torque is 4,837,000 Nm
  • To remove the soil, the cutter has been provided with 176 peelers, 42 disc cutters and 16 reamers
  • To stabilise the ground, the shield is surrounded by an overpressure of up to 4 bar