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Laying of the Hradební stoka

For the Florenc Gate construction project, the so-called Hradební stoka, the drainage tunnel of the fortress walls, had to be laid. It drains the rainwater from a part of Prague's city centre.

Since the tunnel itself is positioned at a very low level, we at PORR a.s. decided to use a trenchless excavation technology, the so-called shield driving. A major advantage of this method is its safety in any case. In shield tunnelling, the front of the inner shell is pushed off and the tunnelling work takes place behind the shield. And thus under its protection.

After the excavation of the 10.5m deep starting pit, the TŠ1, and after the preparation of the guide elements at the bottom of the shaft, which ensure the correct height and direction, we brought the driving shield to the construction site and installed it on 11 October. Due to the minimal use of public space, our PORRians brought the driving shield with 2.56m diameter and a weight of 16t directly from the road into the shaft by means of a mobile crane.

The installation took no less than 3 hours. At the moment, the new section of Hradební stoka, almost 70 m long after completion, is already being worked on.