Rockfall Protection for "Urfahrwänd"

The rock faces known as "Urfahrwände" tower up to 250 metres above the Danube. For millions of years, the river has cut its bed deeper and deeper into the so-called Moldanubic Platform. This partly resulted in steep crags and breaks in walls that endanger traffic on the federal road and bicycle path. Due to this, comprehensive rock consolidation measures have been implemented at this highly frequented traffic route in the past on behalf of the Ottensheim road maintenance authority. This time, the rocks came loose - an occurrence that could hardly have been predicted - due to a change from frosty to thawing weather conditions, as Felbermayr construction manager Maximilian Amenitsch reports: "We arrived at the scene on the very same day and have removed the rocks at a height of some 120 metres. Thus, we could rule out that more rocks would come loose and could lift the total closure of the federal road."

In the course of the findings report carried out by a geologist, however, another rock formation that was in danger of losing its self-support was identified which made the installation of additional rockfall protection fences necessary. The type and scope of the measures was determined together with an expert advisor during an on-site inspection. A total of some 100 running metres of rockfall protection fence was to be installed. Work commenced with the placing of the anchors for the installation of the supports. "We have placed some 70 anchors", says Amenitsch and explains that the anchors reach up to six meters into the rock. And this is more than necessary for the four-metre-high rock protection fence is supposed to withstand an energy input of 1,000 kilojoule. Amenitsch makes an impressive comparison when he says that "this equals the energy produced by a luxury vehicle (weighing 3 tons) driving into the fence at 90 km/h". A mobile crane from the Felbermayr branch in Linz assisted with the installation of the supports and fences. Installing the supports and nets weighing up to 250 kg in the rock could hardly have been done any other way. "Working in the wall is difficult enough as it is. It requires total concentration on professional execution and aspects relevant to safety for you only need to make one false step and you're gone", Amenitsch comments with appreciation on his staff's work in the rocky terrain.

Special precautionary measures also resulted in a traffic volume of some 24,000 motor vehicles per day passing the construction site. In order to ensure safe working conditions, the federal road was closed one carriageway at a time when extensive mechanical work was carried out. The understanding of the road users was exemplary, too. "Overall everything worked very well and one cannot blame car drivers for trying to take a shortcut through the pedestrian underpass to save time", Amenitsch jokingly sums up and is happy about the successful completion of the construction site in early May.  

A rockfall, caused by varying temperatures, required the immediate construction of extra rockfall protection fences.

The drill truck has a range of 32 metres and can be driven by radio control.

Roughly 70 anchors were placed to assemble the supports.

To enable the team to work safely, traffic on the A road was stopped on alternating sides during larger operations.

Road users were particularly understanding during the construction of the new rockfall protection fences.

The supports were placed at a distance of nine metres from one another.

100% concentration to ensure the work on the wall was carried out expertly.

The "Urfahrwänd" tower up to 250 metres above the Danube.

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