MetroMetro Line V.A extension
The V.A metro section is 6,134 m long; it contains four stations: Bořislavka, Nádraží Veleslavín, Petřiny and Nemocnice Motol. The design of all of the stations will be barrier-free. Initial construction operations commenced in April 2010; the line extension will be opened to traffic in 2014.
All underground stations will be excavated using the New Austrian Tunnelling Method (NATM). The double-track running tunnels designed for the section between Vypich and Motol Station will also be driven by the NATM.
The other tunnels will be single-track structures; they will be driven by two full-face EPB tunnelling shields. Compared to the NATM, this technique is more friendly, safer and even quicker. . The monthly advance rate is expected to reach up to 360 m even when driving through problematic ground. It has been applied to approximately 80 percent of tunnels newly built in the world; About 2/3 of the work on the 57 km long Gotthard tunnel, Switzerland, were carried out using this technique.
As mentioned above, the running tunnels on the extension of the Prague Metro Line A from Dejvická Station to Motol Station will be driven by EPB (Earth Pressure Balance) machines. This frequently used abbreviation specifies the type of the full-face shielded machine (balancing pressures during the course of the excavation using the excavated ground).
The shields with serial numbers S-609 (Tonda) and S-610 (Adéla) were manufactured by Herrenknecht AG, Germany. Their names, Tonda and Adéla, were chosen by young patients of the Clinic of Paediatric Surgery, the Faculty Hospital in Motol. The winning proposals were announced during an event held in the Motol hospital, in the presence of Bohuslav Svoboda, Lord Mayor of Prague, Karel Březina, First Deputy Lord Mayor, and Pavel Pilát, general director of Metrostav a.s., who thanked for the collaboration of the hospital ward on naming the machines and handed presents to the children patients, intended to make their time spent in hospital beds at least slightly more pleasant.
The tunnelling machines were transported in parts to BRE1 construction site, which is found east of the Vypich intersection, roughly 500 m before Petřiny Station. Individual parts were lowered to pre-prepared beds at the bottom of a 21m-diameter, 34m deep assembly shaft, braced by secant piles, where the machines were assembled. Then the entire tunnelling complex was joined together to form one unit and finished in the assembly chamber, formed by a double-track metro tunnel section linking to the assembly shaft.
The entire route to Dejvická Station to be driven by the machines can be divided into two main sections. The first section begins on BRE 1 construction site and ends on E2 site, which is located approximately in the middle of the route. The other section continues from the E2, ending before Dejvická Station.
The excavation of the single-track running tunnels by the shielded full-face machines started in April, first in the left tunnel tube (viewed in the direction of the drives), using the S-609 (Tonda) machine. The assembly and preparation of the second machine, marked as S-610 Adéla, proceeds with a three-month lag time.
In total, the two EPB tunnelling machines will drive single-track tunnels at the length of 8,100 m (2x 4050 m).
Extension Dejvická - Nemocnice Motol 2013
Extension Dejvická - Nemocnice Motol 2012
Extension Dejvická - Nemocnice Motol 2011