Open building tunnel

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Open building tunnel
Offenbau tunnel
Open building tunnel
South portal of the Offenbau tunnel
use Railway tunnel
traffic connection High-speed line Nuremberg – Ingolstadt – Munich
place Thalmassing
length 1333 m
Number of tubes 1
Largest coverage 4 m
construction
Client DB Netz AG
building-costs approx. 150 million euros
location
Open Building Tunnel (Bavaria)
Red pog.svg
Red pog.svg
Coordinates
North portal 49 ° 7 ′ 58 ″  N , 11 ° 16 ′ 13 ″  E
South portal 49 ° 7 ′ 17 "  N , 11 ° 16 ′ 33"  E
North portal of the tunnel

The Offenbautunnel (also tunnel Offenbau ) having a 1333 meter long, einröhriger railway - tunnel of Nuremberg-Munich high-speed railway . Between the route kilometers 40.537 and 41.870 it crosses under the Offenbau district of the municipality of Thalmässing , immediately west of the parallel A 9 . The tube accommodates two tracks in slab track , which can be driven on as planned at 300 km / h.

Its construction is considered to be one of the most complex of the nine tunnels on the high-speed line . The order volume is around 150 million euros.

course

In the tunnel, the gradient of the route to the south drops a few meters. The route runs S-shaped in the tunnel : In the direction of Munich, a slight left curve is followed by a straight section, then a right curve. The cover is between 2.0 and 6.50 m. A total of 1162.5 meter long trough structures adjoin the tunnel on both sides.

The Lohen block site was set up south of the tube . Their advance signals to the south are not far from the north portal, advance signal repeaters to the south are in the tube, near the south portal.

geology

The tunnel leads through quaternary clays and sands as well as clays of the middle and brown Jurassic .

Over a length of around 1000 m, the tunnel runs through swellable clay stones ( Opalinus Clay ).

history

planning

In the early conception phase of the route in mid-1985, it was planned to run the route north of Offenbau between Mindorf and Weinsfeld from the west to the east side of the motorway and to lay it in a tunnel at Offenbau. Around the beginning of 1989, the previously planned tour through the Hofberg (east of the autobahn) was rejected for geological reasons and a tour west of the autobahn, via Weinsfeld, Offenbau, Lohnen, and Klein- and Großhöbing, was favored. In 1990 an approximately 1.3 km long tunnel was planned.

From a technical point of view, it would have been sufficient to build the high-speed line in the open building area in one cut. The decision to tunnel under was made because of the already high pollution of the town due to the motorway already running on the edge of the town. Other options, such as relocating the route to the other side of the motorway or even bypassing the open structure, were discarded in the course of the planning approval procedure .

After only the demolition of a barn was planned in the early planning phase, five houses were to be demolished in the course of the approval planning . On December 30, 1991 two Bundesbahn employees visited five Offenbauer families unannounced and announced that their houses would soon be demolished. Several years of delays in resettlement caused by DB u. a. were justified with a lack of funds, were the subject of multiple criticism. Together with a building near Lohen, these were the only buildings that were to be demolished for the new line according to the planning status of 1992.

The Thalmässing municipal council voted in mid-February 1995 to initiate a company land consolidation and to accept DM 940,000 from DB, with which village renovation measures in the two affected districts of Offenbau and Lohen were subsidized.

In mid-1993 and mid-1994 the planned length was 1350 m. According to the planning status of 1999, the tunnel was already planned with a length of 1331 m.

The structure was part of the plan position of the new line section 41 as well as part of the contract section Nord the track. In the planning approval decision, a complete enclosure of the new line in the area of ​​Offenbau was prescribed as well as a limitation of the groundwater lowering during the construction period.

construction

Originally the tunnel was to be built using the cut-and-cover method with a sloping excavation. Construction work began in autumn 1999. In April 2000, geological problems ( artesian confined groundwater ) resulted in bed elevations and slope slides. Floor slabs that had already been concreted sagged in autumn of the same year. A complete construction freeze was the result.

In the course of the necessary rescheduling, five different construction methods were examined. In addition to the geological problems, the severely restricted space between the motorway and the town and the deadline pressure were the difficulties to be overcome. A compressed air drive with bored piles and covers as well as partial lowering of the groundwater was chosen as the new construction method. This is considered to be extremely costly and comparatively tedious, the experience of the executing companies, the quick implementation and the unexpected objections from residents were ultimately the decisive factors. The resumption of construction work was prepared in May 2002 and construction work began in June. The pressure chamber tunneling began on May 12, 2003.

Up to ten pile drilling rigs set around 2,800 piles up to 30 meters long with a total length of around 70,000 meters. In the tunnel section around 2,200 piles were sunk into the ground, in the northern and southern pre-cuts a total of around 600. The 100 to 120 centimeter thick tunnel ceiling was concreted on these piles in blocks of 12.50 meters in length. This was then covered with about one meter of earth to prevent the ceiling from lifting. The tunnel cross-section was then excavated using compressed air propulsion and the material transported away on a narrow-gauge railway . The excavated cross-section was around 150 m².

The installation of the bored piles took 12 months, the compressed air drive ran for another 12 months. Of the 107 blocks in the tunnel, 7 were constructed using the open construction method and 100 using the closed top construction method. Another year had to be allocated for remaining work and the emergency exit in the middle of the tunnel.

The overpressure compared to the surrounding atmosphere was around 0.99  bar , and the workers' entry and exit times were 48 minutes each. A lock with three chambers for people, material (around 30 cubic meters per lock) and large work equipment was used. All workers had to prove their suitability for compressed air by means of a certificate ; In addition, medical monitoring was necessary around the clock. Internal combustion engines could not be used inside the chamber due to the restricted ventilation ; only electric vehicles could be used.

After the tunnel had been temporarily sealed off against the ingress of groundwater, the compressed air was released in March 2004 and the inner concrete shell was installed under atmospheric conditions. The shell was completed in October 2004. According to the railway, up to 300 people were at times employed on the construction site.

The tunnel was part of the north construction lot of the new line, which was commissioned by a consortium of the companies Bilfinger Berger ( Munich ) and Max Bögl ( Neumarkt in der Oberpfalz ).

security concept

Emergency exit of the open construction tunnel

The Offenbau tunnel has an emergency exit at kilometer 41,324. A 22 m long connecting tunnel leads into a 13 m deep stairwell that leads to the outside. At both ends of the tunnel, ramps for road vehicles lead directly to the tunnel portals to the west.

In the area of ​​the north portal, the railway line runs a short distance below the level of the motorway. Here, the crash barriers along the motorway were supplemented by three-meter-high steel planks - so-called load-dropping restraint systems, LARS  - in order to prevent truck loads from falling onto the route.

See also: Route safety concept

costs

According to media reports, the costs rose as a result of the groundwater problems instead of the planned 16 to 90 million euros. In 2005 the total investment was given as around 150 million euros.

Web links

Commons : Open construction tunnel  - collection of images, videos and audio files

literature

  • Open tunnel construction in a difficult hydrogeological environment. In: Railway technical review . 1/2004.
  • Air versus water. In: Civil engineering. 7/2004.

Individual evidence

  1. ↑ a b c d Martin Muncke: Offenbau tunnel. In: Unterirdisches Bauen Deutschland 2005. Bauverlag, ISBN 3-9803390-3-3 , p. 116.
  2. ↑ a b c d SSF Engineers (ed.): Tunnel of the new Nuremberg – Ingolstadt line (NBS). Lot north - Göggelsbuch tunnel / Offenbau tunnel . (around 2005).
  3. ↑ Is the Federal Railroad now switching to the high-speed line to Munich? In: Schwabacher Tagblatt . July 6, 1985.
  4. ↑ District Administrator “definitely does not want to accept” the new ICE route . In: Roth-Hilpoltsteiner Volkszeitung . March 18, 1989, ZDB ID 1264431-6 .
  5. ↑ a b c d Matthias Kronau: Compensation comes to the fore . In: Hilpoltsteiner Kurier . February 14, 1992, ZDB ID 1256658-5 .
  6. ↑ Close “points of contact” with villages . In: Hilpoltsteiner Kurier . August 27, 1990, ZDB ID 1256658-5 .
  7. ↑ On call for three and a half years . In: Hilpoltsteiner Kurier . May 25, 1995, ZDB ID 1256658-5 .
  8. ↑ Schuster angry at Goppel: The letter is outrageous . In: Hilpoltsteiner Kurier . February 16, 1995, ZDB ID 1256658-5 .
  9. ^ Richard Menius: The new Nuremberg – Ingolstadt line . In: Deutsche Bahn . No. 9/10 , 1993, ISSN  0007-5876 .
  10. ^ Deutsche Bahn, Network Division, Regional Area Nuremberg (ed.): New Nuremberg – Ingolstadt line. 12-page brochure dated July 1994, p. 5.
  11. ↑ a b Planungsgesellschaft Bahnbau Deutsche Einheit mbH (publisher): Nuremberg – Munich in one hour. Nuremberg, November 30, 1999 (similar version from January 1999 as mgrobe2.free.fr PDF; 2.3 MB), p. 9.
  12. ↑ Günter Strappler, Heinz-Dieter Könnings: New Nuremberg - Ingolstadt line sticking points in the handling of tunnel projects. In: Felsbau. ISSN  0174-6979 , Vol. 17, 1999, No. 5, pp. 358-366.
  13. ↑ a b c Rolf Syrigos: Citizens of Offenbau get the most expensive artificial tunnel on the ICE line. In: Nürnberger Zeitung . May 8, 2003.
  14. ^ New ICE and upgraded Nuremberg - Munich line - status of construction work in June 2005 Information sheet from DB ProjektBau, Nuremberg.