At the end of February, TANGRA – AV Ltd. completed the tunnel ventilation system for the bypass road of the city of Gabrovo. The project is part of the North-South transport corridor. The tunnel consists of a single tube with two traffic lanes, sidewalks, a safety system, light signaling, fire detection, video surveillance, a control room, and a specialized ventilation system. The main contractor for the entire bypass was the consortium “PSVT,” which includes the companies “Hidrostroy” AD and “Patni Stroezhi Veliko Tarnovo” AD. In mid-2019, they approached TANGRA to execute part of the HVAC works. The project, designed by engineer B. Horozov, included 10 axial high-temperature, reversible jet fans for the tunnel. In normal operation, these fans ventilate and remove vehicle exhaust gases, while in emergency mode, they serve for smoke extraction.
The TANGRA team delivered 11 tunnel jet fans with a diameter of 710 mm, of which 10 were installed and 1 was kept as a spare. The fans have a thrust force of 685 N and are equipped with built-in silencers, vibration and fault sensors, silenced mounts, and safety chains. These fans are high-temperature and reversible, with adjustable airflow capacity. All components are made of stainless steel AISI 316 (1.4404). Before being shipped from the factory in Germany, the fans underwent 3D X-ray testing in operational mode to assess their aerodynamic performance, as well as their electrical and acoustic characteristics. To ensure proper installation, the fans come with adjustable horizontal and vertical stainless steel mounts.
The fastening of the TANGRA fans was carried out using specialized anchor bolts and chemical anchors from FISCHER, Germany.
Together with representatives of the company for Bulgaria, before the start of the installation activities, two test drillings and trial anchorings were performed. After 5 hours, a load test was conducted. The anchors remained firmly in place even under a load of 100 kN (10,200 kg). FISCHER issued a certification for the anchoring system, and following the same principle, all the stands as well as all the safety chains of the fans were mounted and secured. This provides assurance to all parties involved — the main contractors from the “PSVT” Consortium, TANGRA as the HVAC contractor, and also to all travelers passing through the tunnel in the future.
After the successful completion of construction and installation works on June 4, 2020, the Gabrovo bypass was officially opened by the Prime Minister, Mr. Boyko Borissov. The jet fans in the tunnel, delivered and installed by TANGRA, will ensure smooth and safe passage of cars and trucks.
