Blanka tunnel breakthrough in PragueThe final blast took place on 13.01.2011 in the north tube of the Blanka tunnel between Letna and Troja. The tunnel passes under the junction of Korunní and Jana Zajíce streets in Prague. The south tunnel tube has 200 m to go and should break through in February. Work will then shift to the side-tunnels, which will provide ventilation.The Blanka tunnel complex forms the north-western section of the City Circle Road and is currently the largest underground construction project in the Czech Republic. The total length of new road section is 6.382 km, of which 5.5 km is in tunnel. Construction of all tunnels is being carried out by Czech contractor Metrostav a.s. The section comprises three tunnels sections between the Malovanka grade-separated intersection at the northern portal of the Strahov tunnel and the Troja intersection at the new Troja bridge across the Vltava. These are the 1.4 km Brusnice tunnel with 550 m of mined tunnels and the rest in cut/cover; the 1 km cut/cover Dejvice tunnel under Milady Horakove Street, completed in 2010; the 3.09 km Kralovska Obora tunnel with 2,230 m of mined tunnel and the rest in cut/cover. The latter has a ventilation plant cavern with excavated cross-section of 286 sq m and a complicated system connecting the ventilation tunnel to the main tunnels.Blanka tunnel has suffered three collapses during its construction and a shortage of funds, and opening has been delayed until 2014. For more click cz/22 and visit http://www.tunelblanka.cz/ and www.metrostav.cz. 05/11.