TECHNICAL | UTILITY TUNNELING
DANUBE BUNDLE
Two Austrian towns had their utility networks improved in one step with services pipes running through a new shared micro-tunnel, constructed under the River Danube
Above:
Utility pipelines being fed into a pipejacked tunnel below the River Danube, in Austria
PHOTO CREDIT: EVN
Challenges in expanding a utility network and hence services to communities are many and varied, and not least they often include negotiating the local geographical hurdles and blockages – and to do so economically, and in timely fashion. The problems are compounded when multiple utilities
need to be improved for communities. One such set of challenges faced the communities of
Klosterneuburg and Korneuburg in Austria when both needed improvements to multiple utility services. They are two municipalities in Lower Austria, the largest federal state in Austria – and where the energy and environmental services utility company, EVN, is based. The geographical challenge in the particular case of
these towns – and a hurdle for each one of the utility services needing to be boosted – was the River Danube. The towns sit on opposite sides of the famous large
river. EVN’s solution was to construct a single tunnel
culvert under the river bed and then to thread a bundle of utility service pipelines through the tight circular space.
24 | Spring 2023 The range of utilities to be run through the tunnel
are for potable water supplies, gas, electricity, natural heat and also telecommunications. In bundling them together, through the culvert and linking the towns to the greater network, EVN improved the security of supplies and services in the region as well as supporting sustainable energy supplies and the economy.
PIPEJACK TUNNEL The culvert to hold the bundle of utilities was built below the Danube by pipejack tunneling. A 40-tonne micro TBM bored the 460m-long (1509ft) culvert tunnel between relatively shallow shafts beyond each river bank. The pits were constructed with concrete pile walls, and approached by sloping cuts, excavated with braced sheet pile supports. But it was not a straight run for the tunnel to pass
under the river. The tunnel alignment has a slight curve with a horizontal radius of 1600m (1750yd). Over the drive, the depth of cover varies from approx. 5m (16.4ft) beyond the portals, near the river banks, to up to 11m (36.1ft) below the middle of the river bed.
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