Hornboden railway overpass
Construction of a new railway overpass at Hornboden in Grenzach-Wyhlen
Implenia was commissioned to construct a new railway overpass in Grenzach-Wyhlen. The structure was built in a construction pit next to the railway embankment before being moved underneath it using temporary bridges. These bridges were then removed and the four wing walls installed.
When excavating the construction pit, it was discovered that the original plans to lower the groundwater level would not be possible due to gravel deposits and nearby contaminated sites. Consequently, a water-tight lining had to be created both for the construction pit and for the final position of the structure. This was done using underwater concrete base slabs. The construction pit was built as a box with sheet pile walls, while a combination of sheet pile walls and overlapping bored pile walls consisting of small drilled bored piles (30 cm in diameter) was used for the final position owing to space constraints.