Project Description

Separate Position 3 - Engineering, Reconstruction, and Modernization of the Telephone Cable Network and Equipment in DP NKZHI in the Gorna Oryahovitsa-Byala Section

Construction of 2 groups, category 1. Preparation of a working project: A working project has been prepared in accordance with the Employer's technical specification.
Execution of construction, repair, and installation works:
Alongside the railway line in the Gorna Oryahovitsa-Byala section, an optical cable, dielectric, self-supporting, with a track-resistant coating for installation at voltages of 25 kV/50 Hz, is installed above the concrete or iron-lattice poles of the contact network. The cable is secured with anchoring devices (anchors) providing a firm attachment, and supporting devices (rollers) allowing the cable to be suspended on intermediate poles.
Suitable dielectric splices are used for connecting cable lengths and deviations from the cable. These splices are installed underground in shafts when the cable is laid by excavation, or on the poles of the contact network when the cable is installed in the air. The fibers of the optical cables are connected in the splices by thermal fusion splicing, protected at the splice location with heat-shrink sleeves arranged in splice cassettes with a capacity of 6 to 24 fibers.
Deviations from the main trunk cable are made in substations, sub-areas, sectional posts, and cabins (containers) for interstation equipment of the signal and communication network, located in the interstations.
Underground entry into buildings and operational points is carried out through built-in channel networks, where available, or by excavation in non-flammable protective HDPE pipes with sealed ends, leaving a cable reserve.
Branch splices with double-sided reserves are installed at the level crossings for transmitting data from the crossing equipment to the remote information panel and for video surveillance purposes.
In the tunnels, the HDPE optical cable passes through a protective HDPE pipe.
The optical cable is terminated at all stations, separate posts, and power facilities of the power distribution division in the section, either fully or partially, using ODF (Optical Distribution Frame) optical splitters mounted in a 19" standard locking cabinet located in designated rooms for telecommunications equipment, with appropriate dimensions, or on the wall, depending on the type of connectivity.
SDH (Synchronous Digital Hierarchy), Multiplexing Equipment, and Station Concentrator include:
SDH-STM4 transmission system in ATC Gorna Oryahovitsa and Byala Station, multiplexing equipment; SDH-STM1 transmission system in RP Akatsiya, Yantara Station, Petko Karavelovo Station, and Polski Trambesh Station;
Access equipment - MUX (Multiplexer) - low-frequency multiplexing in ATC Gorna Oryahovitsa, RP Akatsiya, Yantara Station, Petko Karavelovo Station, Polski Trambesh Station, and Byala Station;
New power supply devices 220V/48V and grounding for communication equipment in ATC Gorna Oryahovitsa, RP Akatsiya, Yantara Station, Petko Karavelovo Station, Polski Trambesh Station, and Byala Station;
Digital station concentrators for providing specialized communication links for duty officers in ATC Gorna Oryahovitsa, RP Akatsiya, Yantara Station