Major project - Danube development
February 21, 2023 | Markus Lackner
Since 2021, Felbermayr and the Domarin Group, in which the company holds a majority stake, have been working in a joint venture on the Danube development between Straubing and Bogen. Up to May, the navigation channel in the free-flowing section of the Danube and in the lock channel will be deepened by Felbermayr's hydraulic engineering division in this two-year project - the largest to date.
"We are on schedule," says Hans Wolfsteiner, head of the Felbermayr hydraulic engineering division, with satisfaction. With its two construction stages, the project is complex: "We do a wide variety of work here, but in this combination before," he says. Around 150,000 cubic metres of material will be involved in the dredging operation. This will fill in scour holes and create ecological compensation measures.
Construction work for nature and navigation
In addition to the work on the Danube riverbed, a lot of earthworks will be carried out outside the navigation channel along the banks: For flood protection, silted-up side channels will be opened up and additional retention areas created, and embankments and beds secured with 85,000 tonnes of armour stone.
For nature conservation, three gravel islands will be filled, banks will be reclaimed, the Straubing oxbow will be upgraded as a habitat, ecological design elements such as rootstocks and deadwood piles will be placed as wave impact protection and uprooted trees will be deliberately anchored in place. These trees felled into the water create deadwood structures - thus ecologically improving the "riparian habitat". The near-natural structural diversity is a paradise and a welcome nursery for many fish species and other aquatic life.
Currently, Felbermayr hydraulic engineering is deepening the navigation channel at the level of the Sand Harbour by at least 20 centimetres through dredging. The ARGE partner Domarin is mainly implementing the hydraulic work and earthworks in the riverbank area. Felbermayr has been working successfully with the Vilshofen-based group for many years and has been its majority owner since May 2022. This brings advantages to both sides and, above all, greater clout in the market - the current major project is a good example of this.
Hans Wolfsteiner informs us that the work on the construction site depends on the water level: "When the water level is good, we work mainly in the water; when it is low, we tend to work in the riparian area. The challenge in the construction process is the respective reaction to the water level, especially bringing equipment into place. On land, for example, an excavator is quickly available, but on the water it can take several days because the equipment is often tied up elsewhere. In any case, in hydraulic engineering you always have to weigh things up carefully and plan for the long term, Wolfsteiner says.
Low temperatures, freezing wind and bad weather can hardly affect the specialists on site (a team of around 20 on average). "The shipmasters and excavator drivers work in cabins and sailors are also only temporarily outside," says the divisional manager.
Hydraulic engineering for more economic efficiency
One of the primary goals of the Danube development is to ensure that the bottleneck from Vilshofen to Straubing remains uninterrupted even during prolonged low water, thus increasing the economic efficiency of the Danube as a mode of transport. On the first 9.7 kilometre section between Straubing and Bogen, the navigation channel depth will be increased from 2 to 2.65 metres regulation low water level [RNW]. For a Europe Type II vessel, this means a capacity increase of 10 percent or about 140 tonnes of cargo more per voyage, due to this RNW. Coming from the ports of Rotterdam, Antwerp or Amsterdam, and from the ports of the lower and middle Danube, the ships transport mainly fertilisers, animal feed, ore, coal and other bulk goods. RNW is the water level that is reached or exceeded on the Danube on average 94 percent of the days of a year (343 days) during the long-term comparison period.
The client for the large-scale project is the hydraulic engineering infrastructure company WIGES, which has been owned by the Free State of Bavaria since February 2020. The measures for the Danube development and for protection against a 100-year flood are treated together because of their mutual influence. The hydraulic engineering project for the 69 kilometres of river from Straubing to Vilshofen, including flood protection and ecological compensation measures, costs 1.43 billion euros and is thus one of the largest in Germany.
"By optimising the construction process through half-sided work in the navigation channel, shipping traffic can be maintained for the most part," Wolfsteiner adds, mentioning a measure that saves shipping cost-intensive days at a standstill. Hydraulic engineering is one of the most important international areas of Felbermayr's construction business segment. The 140 floating devices include push-boats, hopper barges, stilt-mounted pontoons, long-shaft dredgers and motor vessels. This allows the division to work on almost all of the European inland waters. On the Danube, the heavy-load vessel "Horst Felix", the crane ship F 131 as well as work-deck barges and dredger pontoons are in operation along with motor vessels.
