Main bridge Randersacker

Main bridge Randersacker
	Northern superstructure (2009)
Convicted	Federal motorway 3
Subjugated	Main
place	Randersacker
Entertained by	Autobahn Directorate Northern Bavaria
construction	Prestressed concrete - box girder bridge
overall length	540 m
width	2 × 20.2 m
Longest span	140 m
Construction height	4.0 to 7.5 m
height	16 m
Headroom	14.0 m
start of building	1961/2008
completion	1963/2011
	location

49.738611111111 9.9858333333333Coordinates: 49 ° 44 ′ 19 ″ N , 9 ° 59 ′ 9 ″ E

The Mainbrücke Randersacker is a 540 m long bridge on Autobahn 3 .

The structure is located between the Würzburg-Heidingsfeld and Würzburg-Randersacker motorway junctions. It spans south of Würzburg near Randersacker at a height of about 20 m the Main at river kilometer 260.56, to the left of the Main the Treuchtlingen – Würzburg railway line and the state road 2418 from Würzburg to Winterhausen and to the right of the Main the federal road 13 . As part of the six-lane expansion of the motorway, the bridge was replaced by a new building. After the award at the end of 2006, construction began in summer 2007 and commissioning in July 2011.

Bridge from 1963

Superstructure from 1963

The route of the motorway from 1963 had a clothoid in the course of the bridge with a radius of curvature of 2000 m. In the elevation there was a rounded tub, the longitudinal slope was approximately 3.5%, with a cross slope of 1.5%. The overpass was built with a joint superstructure for the two-lane Nuremberg carriageway and the three-lane Frankfurt carriageway between 1961 and 1963.

Foundation and substructures

The abutments were founded flat , the pier washers were deeply founded with driven piles . The pillars had a full cross-section and were clad with natural stone made of shell limestone .

Superstructures

The superstructure had seven fields and consisted of a prestressed concrete construction with a 33 m wide four-web T-beam that was prestressed in the longitudinal and transverse directions. The overall height was constant at 3.8 m in the side panels. It grew to 5.56 m above the river piers, where there was also a floor slab in some areas to absorb large pressure forces. The width of the T-beam webs varied between 56 cm in the field and 1.5 m above the supports. Cross girders were arranged in the support axes and with a height of 2.9 m and a thickness of 53 cm in the fields twice and in the river opening three times. The concrete deck was at least 28 cm thick. The fixed point of the continuous girder bridge was the right-Main river pier.

The spans for the seven-span bridge from west to east were 75.0 m, 78.0 m, 115.0 m, 80.0 m, 70.0 m, 66.0 m and 56.0 m.

execution

The first bridge was constructed in four sections on falsework . For the falsework towers, a deep foundation was required in the area of the Main.

New bridge construction 2011

Construction status of the southern superstructure in July 2010

The new bridge, which cost a total of € 35 million, consists of two superstructures made of prestressed concrete, each 540 m long. This time the box girder was used as a cross-section. The spans are 57.5 m, 81.0 m, 140.0 m, 81.0 m, 71.0 m, 61.0 m and 48.5 m. The height of the superstructure varies between 7.5 m above the river piers and 4.0 m in the side panels. The total width for the six lanes is 40.4 m.

execution

The superstructures were in the foreland area with falsework and the Main in the cantilever made.

During the construction period, four lanes always had to be usable. This led to the following construction process. First, the northern superstructure next to the old bridge was built on temporary substructures and then traffic in both directions was directed over it. Then the old superstructure, the associated pillars and the abutments were demolished. In the third step, the foundations and substructures for the entire bridge and the southern superstructure were built. After the traffic had been relocated to the new southern superstructure, the new northern superstructure was later shifted to its final position. Finally, the temporary substructures were demolished.

The old, eastern section of the superstructure was blown up on February 28, 2009. On March 5, 2009, the remaining pillars on the Heidingsfeld side were brought down. The transverse displacement of the northern superstructure by approx. 20 meters took place from February 21 to 22, 2011.

Special events

During the demolition of the old bridge on February 3, 2009, there was an unusual traffic accident, which was also referred to as the "miracle of Würzburg". A truck heading towards Nuremberg broke through the construction site barriers during the night due to excessive speed and only came to a stop on a section of the bridge that had not yet been broken off. The driver had to with the help of a fire engine from the cab been recovered, the lorry with a mobile crane .