Cityringen is the largest building project in Copenhagen since the era of Christian IV (King of Denmark and Norway in the period 1596-1648), the founder of Christianshavn – a manmade island constructed in the area between the original city and Amager island.
Cityringen is a completely new section of Copenhagen's underground railway, a ring rail line being constructed in the very centre of the Danish capital city. The entire project includes 17 new train stations built in average depth of 22 m beneath the ground level, the total length of tunnels (drilled with 4 TBMs – tunnel boring machines) will reach approx. 30 km (15 km in each direction). 125 000 pcs of prefabricated reinforced concrete segments brought from Germany will be used to line the tunnel tubes, the project with multiple international participants (managed by General Contractor from Italy) will further utilize abt. 550 000 tons of concrete and abt. 100 000 tons of steel. The whole project is scheduled to be finalized and put into operation in 2018.
As both the bored tunnel tubes and the train stations are situated beneath the level of underground water, all structures must be reliably protected against pressure water. The insulation of tunnel tubes will be provided by the prefab segments with sealed joints, the railway stations will be lined with a waterproofing membrane. A thermoplastic-polyolefin (TPO)-based membrane (thickness 3,2 mm including the signal layer) is complemented with a system offering an additional possibility of grouting, with the insulated areas therefore separated into partial segments by dividing stripes.
The surfaces of the underlying structures (mostly made from shotcrete) are not smooth, hence it is important to shield the waterproofing membrane against potential damages both during the period of construction works and during the designed lifespan of the structure itself. This protection function will be fulfilled by polypropylene non-woven geotextile geoNETEX ZTV/RIL with area weight of 1000 g/m2, supplied by a Czech manufacturer JUTA a.s., and certified in accordance with the respective German regulations for tunnel constructions.