The tunnelled primary collectors are constructed by means of classical tunnelling ca. 30 metres under the terrain surface. They are not directly connected to the street surface network. The aboveground objects of the primary collector are located above the entrance shafts and serve both for access and also for placing of networks and technologies.
Linear utilities of transit mains and technical networks for longer distances are placed in the primary collector.
The dimensions for main primary collectors are nowadays: circular profile with diameter of 5.10 metres, with flat bottom of clear height 4.0 metres.
Unlike the primary collectors, the tunnelled secondary collectors are considered to be a distribution network and their purpose is to distribute networks to individual buildings above the ground. They are tunnelled ca. 5 metres under the terrain surface and equipped with aboveground entrance or ventilation objects. The cross-section profile of the collector depends on placed utilities. The dimensions for the main secondary collectors are dimensions 3.0 metres x 3.3 metres.
The excavated secondary collectors are approximately in the similar depth under the terrain surface as the tunnelled secondary collectors. The collector body is made of cast concrete, partly completed with some prefabricated elements. Unlike the tunnelled collectors, the construction of this type of collectors usually requires vast disturbance of surface communications.