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Tunnel Kreuzstraße Tuttlingen, B311

1. General information

The federal highways B 14 and B 311 cross in the city of Tuttlingen. The federal highway B 311 in extension with the B 31 is an important east-west connection in the southern part of Baden-Württemberg between the cities of Ulm and Freiburg. The federal road B 14 connects the middle centers Rottweil, Tuttlingen, Stockach and Lake Constance. For a long time, the through roads of Tuttlingen and Neuhausen ob Eck formed "bottlenecks" on the route between Ulm and Freiburg. Of the approximately 15,000 vehicles that pass through the B 311 every day, about 11% are trucks. The aim of the B 311 relocation project in the Tuttlingen area was to eliminate these bottlenecks and thus noticeably relieve the core city of Tuttlingen of traffic. The overall B 311 relocation project comprised a total of five subprojects, the most important parts being the Neuhausen ob Eck bypass and the Kreuzstrasse tunnel. With the construction of the new Kreuzstrasse tunnel in Tuttlingen, the two heavily trafficked federal roads B 14 and B 311 were bundled into a single inner-city route and routed in the form of a tunnel along the previous route of the B 14. One challenge here was the very close proximity of residential buildings, access to which had to be ensured during the entire construction period. Planning for the Kreuzstrasse Tunnel began as early as 1983, and two years later the project was classified as an "urgent requirement". The planning approval procedure began in 1989. The final approval for the construction of the tunnel was granted in the summer of 2006.

2. construction design

2.1 Geology and foundation

Different foundation strata are present at the tunnel site. From the west, there is a loose rock layer of Danube clay and slope gravel about 14 m thick. The thickness of this layer decreases after about 200 m to about l m below ground level. Underneath lies rock of limestone and limestone marlstone of the White Jurassic. The entire tunnel lies above the groundwater table.

2.2 Location and cross-section

The tunnel was built using the cut-and-cover method due to the low overburden height of a maximum of 3.50 m. The tunnel is 948 m long. Its length is 948 m. Starting at the west portal, the tunnel initially follows a right-hand curve, then changes to a left-hand curve due to the peripheral buildings, and then twists into right-hand curves of different radii. The circular arcs are connected by transition arcs and straight lines. The smallest radius is R = 200 m. The gradient follows the surface of Kreuzstrasse and has gradients of up to 3.7%. The tunnel consists of a reinforced concrete tube with a rectangular cross-section of 9.70 m width and 5 m clear structural height. The height of the traffic area is 4.50 m. The tunnel is used by two-way traffic, each with one lane of 3.75 m width. Due to the tight radii, the width of the emergency walkways on both sides has been set at 1.10 m. The tunnel will be built with a single lane of traffic. In accordance with the geological situation, the tunnel will have a closed invert for a length of 188 m and an open invert for a length of 760 m. In the area of the closed invert, the tunnel will have an open invert. In the area of the closed invert, the standard thickness of the invert is 85 cm. The tunnel with open invert will be bedded on strip foundations 2.00 m wide. The wall thicknesses are between 70 and 90 cm. Coves reinforce the transitions from the walls to the ceiling. The tunnel ceiling was designed to be inclined in accordance with the transverse slope of the carriageway. Its thickness varies between 85 and 100 cm. Since the entire tunnel lies outside the groundwater and seepage water can easily run off, the tunnel was not designed for water pressure but as a water-impermeable concrete structure. Only the ceiling is sealed against seepage water by a plastic waterproofing membrane with 10 cm of protective concrete. The tunnel was constructed in blocks of 10 m standard length. In the area of the ventilation niches and with a radius of R < 300 m, the block length is 8.00 m. The individual blocks are separated by space frames. The individual blocks are separated from each other by space joints, which were sealed with an internal joint tape and provided with a joint closure tape on the air side. Joint plates were installed in the construction joints between the invert/wall, wall/ceiling. The high point of the tunnel is located approximately in the middle of the tunnel. Breakdown bays have been installed here on both sides. At the same time, this is the location of the underground operations building and the extinguishing water basin. The tunnel's safety concept is based on the 5 emergency exits, whose staircases lead to the surface. With distances of 88 m to 191 m between the escape routes, the maximum distance of 300 m required by RABT 2006 is significantly undercut. In the tunnel entrance areas, noise barriers >. 2.00 m are arranged, which also serve as fall protection.

2.3 Tunnel equipment

The operational equipment is usually controlled automatically by the tunnel control center in the underground operations building in the middle of the tunnel. The tunnel control center is therefore not permanently manned. In the event of malfunctions or alarms, remote signaling takes place to the permanently manned monitoring center at the Tuttlingen police headquarters and the road maintenance center in Spaichingen. From there, it is possible to intervene in the control of the tunnel via the operating and monitoring equipment.

Energy supply

The power supply is provided by the 20 kV ring network of the municipal utilities.

An uninterruptible emergency power supply with batteries for a duration of up to 60 minutes is available for all safety-relevant systems.

Lighting

High-pressure sodium lamps with increased luminous efficacy were used to illuminate the tunnel. The entrance lighting can be switched in 8 stages depending on the difference in brightness between the outside area and the tunnel. The passage lighting is switched in two stages according to day and night.

Ventilation

Fresh air supply is provided by 14 jet fans. In the event of fire, they ensure rapid smoke evacuation through the portals.

Traffic engineering

Traffic flow is controlled by traffic signals, variable message signs, variable message signs, variable message signs/yellow flashers, automatic half-barriers, and fixed signage.

Fire alarm systems

A linear fire detection system (temperature sensor) is installed on the tunnel ceiling. Push-button detectors are installed in the tunnel, in the operations building and in the 5 emergency exits. The fire alarm is reported directly to the rescue control center via the fire alarm control center in the operations building. The central control system indicates the exact location of the fire alarm in the tunnel.

Communication systems

The tunnel has a tunnel radio system (analog and digital) and a loudspeaker system suitable for the tunnel (boundary horns). The video system allows uninterrupted monitoring of the traffic area, emergency exits and portal areas, so that, in addition to manual traffic control, the optimal deployment of rescue forces is possible. There are 11 emergency call stations installed in the tunnel and another 5 in the emergency exits.

Drainage systems

The drainage system consists of slotted channels through which water enters the drainage pipe under the carriageway via baffle shafts. At the two low points, the drainage pipe leads to the catch basins near the portals. In the event of an accident, before the water from the catch basins is pumped into the municipal sewer system, the contents are tested for contaminants. The size of the drainage system is designed for an emergency case with approx. 72 m3 of extinguishing water and 30 m3 tank content of a truck.

Extinguishing water supply

The extinguishing water supply is provided by an extinguishing water basin with a connected pressure boosting system at the high point of the tunnel, from which extinguishing water pipes lead to the 10 extraction points in the tunnel. In the event of a fire alarm, the pressure boosting system is automatically switched on so that the required pressure is available when the fire department arrives.

Coating

After a successful trial coating on partial areas, half of the walls of the entire tunnel were coated with products based on nanotechnology. The coating results in a significant brightening, slower soiling due to its beading effect, and less cleaning effort. Compared to an OS-C coating, the blasting of the walls and the basic filling could be saved and the top coating applied in one work step.

3. Construction

Construction work on the tunnel began on September 29, 2007. An extensive procedure for the preservation of evidence had already begun a year earlier, since the tunnel is located in the middle of the city and the facades of some of the houses bordered on the construction trench. All supply and disposal lines were relocated to the front yards or under the sidewalks. The tunnel was constructed over its entire length of 948 m using the cut-and-cover method in an excavation pit up to 12 m deep. This was done in four construction stages. Due to the inner-city location of the tunnel construction site, one section of the tunnel first had to be passable before another intersection could be closed and work could begin on the next section. Against the background of inner-city construction, the excavation pit was secured with bored pile walls. Approximately 1,700 tangentially arranged bored piles with a diameter of 75 cm and a length of 12 to 18 m were constructed using the double-head rotary drilling method. The bored pile walls were then filled with shotcrete. In the transverse direction, the excavation pile walls were supported against each other with steel girders. In the protection of the bored pile walls, the tunnel floor, the walls and the ceiling were constructed in in-situ concrete as a rectangular profile.

VOB acceptance took place in July 2010. Prior to commissioning, the tunnel's safety concept was tested by fire tests in a large-scale exercise by the fire department, THW, police and DRK. The Kreuzstrasse Tunnel has been open to traffic since February 17, 2011.

4. Literature

[1] Stadt Tuttlingen, Regierungspräsidium Freiburg und Gemeinde Neuhausen ob Eck: Die Verlegung der B 311 bei Tuttlingen, Festschrift zur Einweihung am 17. Februar 2011.

 

 

  • Country: Germany
  • Region: Baden-Württemberg
  • Tunnel utilization: Traffic
  • Type of utilization: Road Tunnel, inner urban
  • Client: Federal Republic of Germany, Land of Baden-Württemberg
  • Consulting Engineer: Lahmeyer International GmbH (design), SSF Ingenieure GmbH (execution)
  • Test engineer: Dr.-Ing. Retzepis, Karlsruhe
  • Construction monitoring: Ingenieurgemeinschaft Setzpfand mbH
  • Contractor: Reisch GmbH & Co. KG/SKS Bau GmbH & Co. KG/Heim Tuttlingen Bauuntern. GmbH & Co. KG
  • Main construction method: Trenchless
  • Type of excavation: Cut-and-cover
  • No. of tubes: 1
  • Tunnel total length: 948 m
  • Cut-and-Cover: 11.10 m wide, up to 12 m deep
  • Contract Volume: 24 mill. Euro (roughwork), 3.7 mill. Euro (operating technology)
  • Construction start/end: 09/2007 till 02/2011 (41 months)