The “Královopolský Tunnel” Tube Has Been Bored Through

11. 05. 2010

On 25 March 2010, the “Královopolský Tunnel” tube was ceremonially bored through in the Žabovřesky metropolitan district of Brno. It makes up a part of the large city ring road which, after its completion in 2012, will significantly decrease the traffic density in the centre of Brno. With respect to the complex geological conditions, a special German system of tunnelling has been developed for the tunnel excavation. The investor of the new tunnel is the Road and Motorway Directorate of the CR. The project is funded from the State Fund for Transport Infrastructure, and through contributions made to it by the Statutory City of Brno. The total price of the work will be approx. CZK 6.5 billion.

The construction makes up a part of the large city ring road and is located in the territory of the Královo Pole and Žabovřesky metropolitan districts. The major component of the construction comprises of two tubes of driven tunnels. Tunnel I is 1,237 m long, and Tunnel II 1,258 m long. Besides the tunnels themselves, the construction includes another 450 structures and operational units. The dense surface housing with related underground services and transport communications on the ground, together with the specific geological conditions of the Brno Neogene clays (“tégl”) place the construction of the tunnels and related structures of the Dobrovského large city ring road among the absolutely unique civil engineering constructions in the Czech Republic. The tunnel overburden ranges from a mere 6 m at provisional portals to the maximum level of 21 m.

“Unique technologies had to be applied on the site, especially because of the extreme and complex geological conditions and so that maximum safety would be secured for the workers and the construction surroundings,” said the CEO of the Road and Motorway Directorate, Alfred Brunclík, today.  Special excavation methods were developed with respect to the complex geological conditions. It is the German method based on the HEBREX welded steel components and quick-hardening injected concrete. The intermediate insulating foil is subsequently fixed to the primary lining created as described above, and the inner permanent lining is made of reinforced-concrete.

As an additional measure to eliminate the risk of emergency situations during construction works in accordance with the requirements of EU directives, surface structures were secured by means of “compensatory grouting”, i.e. the controlled lifting of structures as they were sinking due to excavation work. The scope of compensatory grouting in compliance with the tunnelling legislation is extraordinary, having no parallel either in the Czech Republic or in Europe. The investor and the constructor respect the changes in the scope of the construction caused by law amendments and revisions of standards (environmental impacts, anti-noise measures, etc.), and also additional requirements of the city inhabitants affected by the construction.

The signalling system and safety equipment in the tunnels will comply with the required European parameters. An automatically controlled system of venting allowing the extraction of polluted air will be installed in the tunnels. In the case of fire, it will be possible to extract up to 250 m³ of air per second from any fire location. The lighting of the tunnels will be fully automated, including emergency systems, with the option of adapting to specific conditions in the tunnel and its close vicinity. The system of variable traffic marking will respond to current conditions both in the large city ring road and throughout the whole of Brno.

The major investor is the Road and Motorway Directorate of the CR. The funding of the construction is secured from the State Fund for Transport Infrastructure. The Statutory City of Brno has also contributed to the construction from the combined funds. The total price will be about CZK 6.5 billion. The opening of road no. I/42 of the large city ring road to traffic is planned for 2011, and the final completion of the work for May 2014.