Mrázovka Road Tunnel - NRTM

Prague City Municipal Office 
Section of Municipal Investor
Vyšehradská 51 
110 00 Prague 1 

VIS a. s.
Bezová 1658 
140 00 Prague 4 - Braník

PUDIS a. s.
Nad vodovodem 2 
100 00 Prague 10 

SATRA s. r. o.
Sokolská 32 
120 00 Prague 2 

ASSOCIATION OF SUPPLIERS
Metrostav a.s.
Koželužská 2246 
180 00 Prague 8 
(head of the association)

Subterra a. s.
Bezová 1658 
140 00 Prague 4 

The Mrázovka tunnel is part of the Prague City circuit, especially the section Radlická Street - Strahov Tunnel in Prague 5 - Smíchov.  At the end of the bridge over Plzeňská Street in the direction from Strahov Tunnel there are two parallel three-lane tunnel ducts going from the northern portal - the eastern duct and the western duct. In the   point of disentanglement, both ducts are branching out into double-lane tunnels that continue the city circuit and into single-lane tunnels that are connected to the level crossing in Radlická Street.

 

The Mrázovka Tunnel passes an area with variable, highly unfavourable geological conditions so that from the northern portal an exploration gallery was driven. Part of the tunnel passes under a low hanging layer with a built-up area on the surface. The driving was performed using the New Austrian Tunnelling Method. The primary lining is made of shot concrete of 250-500 mm of thickness,  reinforce compartment arcs, grids and radial anchors. An intermediate foil insulation is installed around the whole perimeter of the tunnel. The final lining is made of armoured monolithic concrete B 30. 

 

In the unfavourable geological conditions, vertical segmentation of the stope was necessary. Micro-pilot umbrellas under the tunnel vault, renovation and compensation injections and an extensive monitoring system were used  under the built-up area. The tunnel also includes and air-duct, air-conditioning room, transformation station, pump station and technological and controlling equipment.

 

The length of the driven part is 1 004 meters in the western duct and 837 meters in the eastern duct. The driven profiles are 165 square meters with the three-lane tunnel, 115 square meters with the double-lane tunnel, 84 square meters with the single-lane tunnel and the point of disentanglement has a profile of 324 square meters. The total stope volume  of the driven tunnels is 351 778 cubic meters.