Hedemünden bridge over the Werra valley

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Werra valley bridges
The bridges of Laubach seen from

The Werratal bridges Hedemünden are sorted a highway - bridge of A 7 and a railway bridge of the Hanover-Würzburg high-speed railway . You are to the east of Hann. Münden in the south of Lower Saxony (Germany).

The buildings, which run parallel at a clear distance of about 33 m, span at Laubach between Hann. Münden and Hedemünden the Werra , the B 80 and the railway line from Kassel to Eichenberg at a maximum height of 59 m above ground.

Highway bridge

history

The first bridge on a contemporary postcard
Pillar of the motorway bridge
View of the Werra below the bridges

In 1937 the first motorway bridge was put into operation, which was a five-span steel lattice structure. It was blown up by German pioneers towards the end of the Second World War on April 5, 1945, in order to stop the advancing American troops.

The new building was carried out until 1952 with unchanged spans and solid steel wall girder constructions. For comparison purposes , the superstructure of one directional carriageway was carried out with an orthotropic carriageway slab and the other with a reinforced concrete composite slab . Two workers had a fatal accident during the construction work; a plaque is dedicated to them on a bridge pillar. Due to the widening of the motorway to six lanes, the superstructures were replaced with steel composite hollow boxes between March 1987 and November 1993. The construction costs were around 35 million euros.

The widening of the motorway bridge should be carried out at the same time as the construction of the railway bridge to reduce interference. Since the construction of the new line was considered to be time-critical, the reconstruction of the motorway bridge was brought forward so that it could be carried out largely in parallel with the construction of the railway bridge.

construction

The route of the motorway has a trough in the area of ​​the bridge and rises in the direction of the abutments by about 5 percent. The 51 m high and 21 m wide pillars as well as the abutments are clad with red sandstone , consist largely of the rammed concrete from the first construction from 1933 and have a flat foundation . The total span of the five-span bridge is 79.93 m + 95.97 m + 96.00 m + 80.00 m + 64.00 m = 415.90 m. The construction height is constant 5.85 m. The carriageway slab width of the two steel composite box girders is 14.7 m each, the floor slabs of the box girders are 4.0 m wide.

Construction of the renovation

First, next to the existing bridge, the new western superstructure was erected on four auxiliary pillars made of reinforced concrete with external dimensions of 4.0 m × 6.0 m. After the traffic had been relocated to this, the old bridge was demolished, the pier heads widened and lengthened and the eastern superstructure was installed. In the following, the traffic was transferred to the eastern superstructure and the western superstructure was moved from the auxiliary pillars to the main pillars. Finally the auxiliary pillars were demolished.

Railway bridge

Pillar of the railway bridge

The double-track railway overpass structure with a length of 415.5 meters is part of the high-speed line Hanover – Würzburg ( route kilometers 120.5). The structure was built between 1986 and 1989 at a cost of around 20 million euros. Immediately southwest of the bridge is the Mündener Tunnel , 700 m further northeast, after a section with the Lippoldshausen transfer point , the Rauhub tunnel .

To the north of the bridge, the route climbs around 96 meters to the Jühnde overtaking station .

The Werra Valley Bridge is one of the most controversial structures on the new Kassel – Göttingen section.

planning

In the pre-routing of the new line from 1972/1973, the crossing of the Werra was also planned in the Göttingen variant north of Laubach.

For several years, Deutsche Bahn, Mündener citizens, the city, authorities and the builders of the planned motorway bridge discussed the necessity, location and design of the bridge.

When the railway bridge was planned, plans were already in place to expand the motorway from four to six lanes . The result of the regional planning procedure envisaged a viaduct that should be as close as technically possible to the motorway bridge ( traffic route bundling ). This corresponded to a distance of 58 m. The concept of building three bridges (one each for the two lanes of the motorway, one for the railway line) met with bitter resistance. This three-bridge solution was provided by the city of Hann. Münden, the district of Göttingen and the district government of Braunschweig rejected. They feared an excessive accumulation of structures in the Werra Valley and called for a joint single-bridge solution for the motorway and the new line.

Ultimately, the Lower Saxony Ministry of Economics and Transport and the Federal Railroad invited five engineering offices to an ideas competition in 1982. On April 28, 1983, a jury of eleven experts selected two favorites from seven proposals: a combined rail and road bridge on the existing pillars - the tracks of the new line were to be laid below the lanes of the motorway - and a two-bridge solution. Four of the five working groups preferred a one-bridge solution, while one advocated a two-bridge solution.

The jury finally voted six to five in favor of the "double-decker solution" developed by Fritz Leonhardt . Feared vegetation damage in the valley and excessive impairment of the valley view spoke against the three-bridge solution. Due to the risk of accidents, the Federal Minister of Transport spoke out against the double-decker solution. Furthermore, susceptibility and risks from accident-related damage, doubts about the stability of the planned use of the existing pillars, 30 percent higher costs and the high structural effort of the necessary line merging of the two routes would have argued against a double-decker solution. In his memoirs, Leonhardt, who was 74 years old at the time of the decision, described not building one of the most beautiful bridges as a disappointment. The bridge was designed in such a way that even unlikely accidents on the motorway would not have endangered the safety of the railway bridge.

The two-bridge solution thus entered the planning approval process.

Foundation and substructures

Werra valley bridges from the haarmann hut

The foundation of the pillars and abutments was done flat on the existing red sandstone. The southern abutment is the fixed point of the bridge, which must transfer horizontal forces of a maximum of 14 MN from braking or starting the trains into the subsoil. At the northern abutment there is a maximum longitudinal deformation of 55 cm, where the rail extension is also available. The approximately 10 m wide pillars are accessible on the inside and clad with sandstone on the outside. They taper upwards with a suit of 50: 1.

superstructure

The superstructure is designed as a continuous beam with five fields. The cross-sectional shape consists of a steel composite structure with a single-cell hollow box cross-section made of steel. The webs of the box girder are connected to the transversely prestressed reinforced concrete deck via belts 0.75 m wide, on which head bolt dowels are welded . The box girder is 7.0 m wide at the top and 5.0 m wide at the bottom. With a superstructure width of 14.3 m, the spans are 76.0 m + 96.0 m + 96.0 m + 80.0 m + 67.5 m. The constant construction height is 6.59 m, which corresponds to a slimness of about 1/15 of the maximum span.

The usual longitudinal prestressing of the concrete in the section above the pillars was dispensed with for the deck . Since the construction method, which was carried out for the first time, was not regulated in the building regulations, approval had to be given in individual cases by the Federal Railway Central Office in Munich . Extensive investigations and statements were required for this.

Construction work

The bridge was assembled by assembling five cross-sectional parts, each 22 m long, in sections on the northern abutment and then pushing in the hollow steel box using the incremental launching method . The in-situ concrete slab was subsequently supplemented with a formwork carriage in sections 16 m long.

literature

  • Federal Ministry of Transport: Bridges on the federal trunk roads 1994 . Verkehrsblatt-Verlag, Dortmund 1994, ISBN 3-89273-070-9 .
  • Knut Reimers, Wilhelm Linkerhägner: Paths into the future. New construction and expansion lines of the DB . Hestra Verlag, Darmstadt 1987 ISBN 3-7771-0200-8 .

Web links

Commons : Werratalbrücke Hedemünden  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c d e f g Federal Minister for Transport / Minister for Economics, Technology and Transport of the State of Lower Saxony (Ed.): Werratalbrücke Hedemünden . 32-page brochure, approx. 1994, pp. 10-15, 28.
  2. ^ DB project group Hanover-Würzburg (North) (Ed.): New Hanover-Würzburg line: Jühnde , 14-page leporello dated October 1, 1984.
  3. ↑ a b Deutsche Bundesbahn, Federal Railway Directorate Hanover, Project Group Hanover – Würzburg North of the Bahnbauzentrale (publisher): New Hanover – Würzburg line. The Göttingen – Kassel section. 36 A4 pages as of October 1983, Hanover 1983, p. 6.
  4. ↑ Central Transport Management Mainz (ed.): New Hanover-Gemünden line . Plan 410.4101Nv101. Edited in January 1972 Langhanki , drawn in January 1972 Bönjer , plan dated February 1, 1972 as of November 20, 1973, sheet 2 of 2.
  5. ↑ a b c d e f Deutsche Bundesbahn, project group Hannover – Würzburg North of the Bahnbauzentrale, Bundesbahndirektion Hannover: The new line Hannover – Würzburg. The Göttingen – Kassel section . Brochure (36 pages), October 1983, p. 29 f.
  6. ↑ a b c d e f Michael Baufeld: The railway is building bridges again . In: Hartmut Mehdorn (ed.): Railway bridges - civil engineering and building culture. Eurailpress Verlag, Hamburg 2009, ISBN 978-3-7771-0398-3 , pp. 121-139.
  7. ^ Fritz Leonhardt : Master builder in a revolutionary time . Deutsche Verlagsanstalt, Stuttgart, 1984, ISBN 3-42102-815-X , p. 296 f.

Coordinates: 51 ° 24 ′ 19 ″  N , 9 ° 42 ′ 54 ″  E