LOCATION Vantaa, Finland

INSTALLATION 2013 – 2014

Ring Rail Line is a passenger transport double railway track. When finished, it is going to interconnect the existing suburban line terminating in Martinlaakso region (west of the airport) with the main railway line linking Helsinki and Tampere (east of the airport) – thereby also establishing a high speed connection between the international airport in Vantaa and the centre of Finland´s capital city. The entire project includes 5 new train stations, total length of the newly built railway track is 18 km (8 km running underground). The trains will travel at speeds up to 120 km/h, a trip from downtown to the airport will take approx. 30 minutes. Passengers arriving from the north will change to Ring Rail Line in Tikkurila station from where they will be brought to the airport in 8 minutes time. The new railway track is sheduled to be put into full operation in the second half of 2015.

The tunnelling of the new track´s sectors began in 2009. In the course of construction works, multiple seepages of water containing propylene glycol (used for aircraft deicing) and substances generated in the process of its decomposition were detected underneath the airport´s runway. As a result of it, extensive colonies of microorganisms producing hydrogen sulphide (H2S) grew in the area. It´s a well-known fact that hydrogen sulphide is potentially dangerous to concrete, reinforced concrete and steel structures.

As soon as the seepages occured, it was necessary to take the necessary construction measures and the original project was changed. In the affected sections a “tunnel-within-the-tunnel” concept was implemented. The bottom of the tunnel´s construction is now represented by a monolithic reinforced concrete, the walls and the upper vault were constructed using ferroconcrete prefabricated blocks. The entire “inner tunnel” must have been encased in a waterproof (seepages) and gas-tight (odour issue) insulation layer with necessary chemical resistance. All the requirements for the insulation layer were fulfilled by a Czech product – JUNIFOL T. Polymeric geosynthetic insulation sheet with 2,2 mm thickness was supplied with a white signal layer providing an easier identification of potential damages and improving the lighting conditions at the jobsite.

Ring Rail Line is considered one of the most important infrastructure projects in Finland. The original estimation of costs amounted to the level of 600 mil. EUR; however, the new circumstances that emerged during the construction works caused an increase in costing by tens of millions of euros.

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