Thousands of Prague residents came to see how the metro is being excavated

Prague - More than 8500 people came today to Prague's Vypich to see how the metro is being tunneled. The city hall and the company Metrostav organized an open day for them at the construction site of the metro line A extension from Dejvice to Motol. They could view the already excavated tunnels as well as the tunnel boring machine, which city and transport officials ceremoniously named Adéla.
The construction of four new metro stations began a year ago. In April, the first special tunnel boring machine named Tonda was put into operation. According to the representatives of Metrostav, it has tunneled 220 meters in the rock towards Dejvice and has about 230 meters left to reach the location of the new Petřiny station.
A second machine should join it at the beginning of July to bore a parallel tunnel. City representatives, transport officials, and Metrostav today named it Adéla. The names for both machines were suggested by children from Motol Hospital. "I wish Adéla to be just as efficient as Tonda, and may we quickly cover those six kilometers," said Mayor Bohuslav Svoboda.
The length of each machine exceeds 100 meters, weighs about 900 tons, and the diameter of the front shield is six meters. It is capable of tunneling up to 15 meters per day. Four ten-member crews are needed to operate it.
The machines disrupt the rock using a rotating head. The excavated material then travels to a loading chamber, from where it is moved onto conveyors. The mined tunnel is immediately secured with reinforced concrete linings, leaving no free space. Altogether, both machines will excavate single-track tunnels with a total length of 8.1 kilometers.
Visitors could also view other special equipment used by the builders while tunneling. Mine rescue workers demonstrated their equipment to the public.
According to Deputy Mayor Karel Březina (ČSSD), the tunneling should be completed sometime around the turn of the years 2012 and 2013. Then, tracks and technology will start to be installed. The first metro trains are expected to run in 2014. "For this to happen, we must not encounter any problems. So far, that has not happened," added Březina.
The new section of the Prague metro from Dejvická station to Motol station will measure 6.134 kilometers. It will include four new stations: Červený Vrch, Veleslavín, Petřiny, and Motol. The construction is being carried out by a consortium of companies Metrostav and Hochtief.