Building a tunnel involves adapting the area to new transportation needs. In the case of the Tramway to Mistrzejowice, one of the biggest challenges is the reconstruction of the Sudół Dominikański. It involves modifying the shape and course of the river and adapting it to the new development. 

The existing section of the Sudół Dominikański watercourse will be demolished: from the Młyńska Street/Macieja Miechowity Street intersection to the connection with the canal running from the Młyńskie Roundabout to the Prądnik River. The tram tunnel will be built in the footprint of the old segment. Water will be routed under the western roadway of Młyńska Street, parallel to the decommissioned route. The length of the reconstructed canal will be 388.65 meters (or about 400 meters including chambers).

Another important aspect is the appropriate selection of construction materials and implementation technology. The aim is to ensure durability and watertightness and to support works made in urban conditions in accordance with the schedule. The new canal consists of 191 reinforced concrete precast elements with internal dimensions of 3.00 x 2.25 x 2 m. Each one weighs 10.8 tons: that’s as much as 200 capybaras! Each element is embedded in a specially prepared excavation, protected in advance by a casing made of Larsen watertight sheet piling in the light of the new channel. It is then precisely assembled into the remaining segments.  

At the end of last week we began embedding the first prefabricated elements and have already completed 24 meters of the new canal!

A Larsen sheet piling is a steel structure used in geotechnical engineering to stabilize slopes, embankments or excavations.