We participate in the modernization of the technological equipment of the Lochkovský and Komořanský tunnels on the Prague Ring Road. This modernization was necessary after eleven years of operation. The main part of the project involves the replacement of ventilation system - a total of 42 jet fans (which are arranged in pairs or in groups of three). The project also includes the installation of fire dampers, emergency lighting, a radio calling system, system of the detection of dangerous goods and upgrade of SOS cabinets. In both two-tube tunnels the anti-skid surface of roads are also renewed. Work can only be carried out on weekends.