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Viktoria TBM Bores through First 1,000 Meters

Released: 15. 12. 2016

Viktoria TBM Bores through First 1,000 Meters
As of today, Metrostav specialists have bored 1,008 meters of the northern section of the Ejpovice railway tunnel. The most important part of the reconstruction of the railway section between Rokycany and Pilsen, this underground work is 4,150 meters long and passes below the hills known as Homolka and Chlum. The general contractor is a consortium of Metrostav and Subterra, while the investor is the Railway Infrastructure Administration.
“In the course of boring the southern section of the tunnel, we already had to deal with the complicated geological conditions below the Homolka and Chlum hills, where we encountered hard spilite rock and an abnormal amount of inflowing water. We are doing our best to put the experience that we have gained previously into practice in the northern section of the tunnel, but the geological makeup there changes unexpectedly meter by meter. For example, unlike in the first section, we hit spilite rock at the very start and in many places; it’s present throughout the entire profile of the tunnel,” reported Head of Construction Tomáš Kohout.
The Pilsen-Rokycany railway is part of the core trans-European transport network, as well as the Third Rail Transit Corridor, which leads from Prague to Pilsen and Cheb, as far as the Czech-German border. The new tunnel will reduce the length of the railway in this section by more than six kilometers, reducing travel time by nine minutes. Once the entire line is modernized, a journey from the Czech capital of Prague to Pilsen will take less than an hour. Currently, a train trip between the two cities lasts one hour and 35 minutes.
The Viktoria tunnel boring machine (TBM), a younger sibling of the Tonda and Adéla TMBs that bored Line A of the Prague subway, began eating its way into the hills at the end of January 2015. It took nearly one and a half years to bore the 4,110 meters of the southern part of the tunnel. The first half of the project was completed in June of this year, when some 10,000 spectators came to see the bore-through ceremony in the Pilsen district of Doubravka. Manufactured by Herrenknecht in Schwanau, Germany, Viktoria weighs in at some 1,800 tons and is 115 meters long, while featuring a cutter head with a diameter of nearly 10 meters. The heaviest parts of the machine were transported to the Czech Republic in an environmentally friendly manner by ship. The tunnel boring technology deployed in Ejpovice represents one of the most modern tunnel construction methods. Its principal advantages include speed and safety. Viktoria is a convertible machine, which means that it can function in several modes that allow it to bore through both soft soil and solid rock. The machine creates a completely finished tunnel with walls built from concrete rings composed of seven plus one segments. Each ring is two meters wide and 0.4 meter thick. Rings are made in Dýšina, approximately two kilometers from the construction site. More than two thousand rings are needed for each tube of the tunnel.
Boring Supervisor Štefan Ivor, whose experience includes work on sites in Iceland and the Prague subway, commented, “Before beginning the work, we drained water from Homolka to mitigate problems involving underground water during the boring process. Once we crossed the problematic areas, we closed up the openings in order to allow the groundwater to return to its normal level. I'm confident that at the beginning of 2018, we'll be able to invite people from Pilsen and elsewhere to welcome the tunnel boring machine when it emerges at the exit portal in Doubravka for the second time,” he added.
The project is co-financed by the Czech government under the State Transport Infrastructure Fund and the EU under the Cohesion Fund within the framework of the Operational Program ‘Transport’ for the years 2007-2013. Subsidies will amount to a maximum of CZK 3,419,440,199.

For more information contact:
Vojtech Kostiha
Spokesperson Metrostav a.s.
Tel.: +420-266 019 715
E-mail: vojtech.kostiha@metrostav.cz

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