1. Description of Area and Building Plot

The extension of metro line A is located in the north-western part of the capital city of Prague. It crosses the city districts Prague 6, Prague 5 and Prague 17. The metro feeder cable of 22 kV overlaps to the city district of Prague 7. The longest part of the line and the majority of the metro stations are situation in the built-up part of the community. Mainly for that reason, the line is designed as a driven line.

2. Purpose of Construction

The goal of the line A extension with high-capacity rail traffic is better quality of transportation sevices in the north-western sector of the city.
The basic transportation and city zoning motivation behind the metro line A extension is the improvement of radial connection of local inhabitants to the city center ( especially shorter transportation times) and also transportation safety and comfort of the passengers.
In respect of the environment, the existing volume of surface transportation will be limited. The noisy bus transportation is a very negative influence on the environment (exhaust gases and noise).
In respect of the transportation provider, an optimized design of metro and surface transportation is expected with minimum operating costs on condition all timing and capacity limits are observed.

3. Construction phasing

The construction of the Prague metro line A from Dejvická station is scheduled in two phases. The first phase of the construction (line V.A) is designed as a temporary terminal station Petřiny. The remaining part of the line (line VI.A) will be constructed in the second phase.

4. Approximate construction specification

Construction length Line A extension 12 630 m
of which V.A 4 550 m
VI.A 8 080 m
Maximum decline 39.5 ‰
Number of stations: 8 stations
Deepest station Bílá hora 44 m under the ground level

5. The Concept of Line Tunnel Construction

Tunnels on the line are mainly designed as single track driven tunnels. This is the best solution for a metro line with island platforms are planned as the most suitable platform solution for its easy passenger orientation and comfort. The continual driving of single track tunnels with constant circular profile can be performed by the modern technology of TBM driving machines without negative impact on surface buildings. Ground depressions over tunnels driven with this technology are hardly measurable (1 – 2 mm). This eliminates the risk for the investor of refunding owners of building in the zone influence by tunnel driving. This aspect is all the more convincing lately because the compensation for damages for building owners are often speculative and considerably exceed the actual value of surface buildings. Another advantage of this technology is the elimination of blasting operations which is sometimes hysterical protests on the part of building owners which is however not justified in the least (see Driving of double track tunnels on the construction section 13 of metro line IV.C2).
Another advantage is the economy and speed of tunnel driving. This technology allows a driving speed of 300 meters per month, best performance is 500 - 600 meters per month. It should be reminded at the same time that this technology can be used to drive long section (several kilometers) where there is no need to provide more annexation for the construction site. This is a big issue especially in the section from Dejvická station to Petřiny station.

6. Expected schedule of V.A line construction

Zoning approval in 2008
Building permission issued in 2009
Start of construction in 2010
Start of operation in 2013
End of construction in 2013