Freiburg secures crumbling Old Town retaining wall

Freiburg is stabilising a retaining wall beneath a restaurant terrace after inspections found that it could collapse, SRF reported. The work below the terrace of the Moroccan restaurant des 3 Rois is expected to cost around 400,000 Swiss francs.

The terrace has been closed throughout the summer because the wall beneath it is deteriorating, making the structure unstable. Part of Freiburg’s Old Town stands on a rock face high above the Saane river.

“Parts of the wall have shifted,” said Dario Carrera, the city’s project manager for natural hazards. Geologist Benjamin Nowak said inspectors had found cracks and deformations in the wall, while the rock beneath it was heavily weathered.

Specialists are drilling five metres through the wall with a hydraulic drill until they reach the rock. They are then embedding iron rods in concrete to anchor the wall back into the rock.

Several cavities currently exist beneath the wall, meaning its stability cannot be guaranteed, Nowak said. The so-called micropiles are intended to ensure that the load is carried by the sound section of the rock.

The problem is not limited to the restaurant terrace. The entire outer row of buildings in Freiburg’s Burgquartier district stands directly on a rock face, and the retaining wall has repeatedly suffered damage that needs to be repaired.

“Because the rock is weathered, walls or parts of buildings repeatedly end up no longer standing on sound rock,” Nowak said. Measures have been taken to address such problems for centuries, including old masonry pillars built hundreds of years ago to support the wall.

“We are constantly making repairs,” Nowak said, adding that safety was ensured and people could continue living in Freiburg’s Old Town.

The costs will be shared by the city of Freiburg, the canton and the property owner.