S 7 Fürstenfeld Expressway, Dobersdorf - Heiligenkreuz Section, Contract Section 1
Client: ASFINAG (Motorway Financing AG)
Development Period: since 2008
The 29 km long new construction of the S 7 Fürstenfeld expressway starts at the Western end from the A 2 Southern Motorway at Riegersdorf and runs towards Southeast up to the Hungarian border at Heiligenkreuz.
The Contract Section 1 within the eastern part of the road comprises primarily three large bridge structures. The valley crossing Dobersdorf is built with eight spans and a total length of 292 m. The six-span bridge across the Dobersdorferwaldbach is characterized by a pylon height of up to 18 m and a length of 180 m. The valley crossing L406 with seven spans holds a total length of 264 m, a maximum pylon height of 21 m and a span width of up to 40 m.
For this project, BGG Consult attends to the fields of engineering geology, hydrogeology, geotechnics and geomechanics, starting from the tender phase. Based on numerous underground investigations as well as soil mechanical and rock mechanical laboratory tests, geotechnical expert's reports have been prepared for each bridge structure.
Subsequently, the tender project and the detailed planning have been accompanied with the specific expertise.
During construction, the relevant measures in the fields of geotechnics and hydrogeology are supervised and the respective questions dealt with.
In order to verify the actual underground situation, the drilling of one bored pile was supervised at the location of each pylon.
Foundation of Bridge Pylons:
The foundation of all the pylons and abutments was carried our by large diameter bored piles in Miocene sediments that occur along the route in a varying succession in form of silt, sand and gravel. In the area of the valley crossing Dobersdorf, a finerained cover layer with a thickness of up to 20 m was found on top of the Miocene. In order to obtain economical pile depths, the skin friction of the cover layer has also been taken into account with a respective reduction.
In addition, it had to be considered, that a pylon at the valley crossing L406 was situated within a creeping slope. This was taken into account for the dimensioning by consideration of a creeping load.