Tunnel Communication PDF

CHAPTER XXXII TUNNEL COMMUNICATION 32.1 Indian Railway has provided various sizes of tunnels on the IR network of varying lengths. These tunnels can broadly be categorized in three categories i.e. tunnels less than 500...

CHAPTER XXXII TUNNEL COMMUNICATION 32.1 Indian Railway has provided various sizes of tunnels on the IR network of varying lengths. These tunnels can broadly be categorized in three categories i.e. tunnels less than 500 meters, more than 500 meters to 5Km and tunnels more than 5Km length. Requirement of integrated communication needed for the above categories will be slightly different. Tunnel Communication system in tunnels where ever provided on Indian Railway shall be able to provide communication need to the following: (i) Tunnels less than 500 meters length. (ii) Tunnels more than 500 meters to 5 Km length. (iii) Tunnels more than 5 Km length. 32.2 Type of communication Systems in Tunnels: 32.2.1 Radio Communication System: Following communications are to be extended as per Railway Requirement in Tunnels for communication during maintenance and constructional blocks, communication in the train in between Guard & Driver, Emergency radio communication between driver, guard, station master & Cabin, Train Control etc: (i) VHF Simplex: The frequency Bands 146-163MHz for VHF Simplex communication are allotted in Indian Railways.The VHF simplex communication being the lifeline of train operation, Tunnel Radio System should be able to provide an uninterrupted radio communication between the radios located anywhere inside a tunnel (inner tunnel) and also between radios of other tunnels(inter tunnel) of the same network. (ii) LocoTrol:The present frequency Bands 424 - 430 MHz for LocoTrol are allotted in Indian Railways. (iii) GSM-R/LTE:The frequency Bands 876-915 MHz(Uplink) & 921-960 MHz(Downlink) for GSM-R are allotted and 700 MHz band are recommended to be allotted for LTE in Indian Railways. (iv) TCAS:The frequency Bands 405-512 MHz for TCAS are allotted in Indian Railways. (v) TETRA: The frequency Bands 370-430 MHz for TETRA are allotted for Railways. The Tunnel Radio System shall provide an uninterrupted radio communication inside tunnel with the headquarters and operation centers and handheld devices of the tunnel operator’s staff, emergency staff and trains which pass the tunnel. It shall be possible to continuous coverage over the entire length of the tunnel, Indian Railways Telecom Manual - 2021 Page 383  clear audio throughout with no interference, reliable system operation under harsh tunnel environmental conditions, trunked radio channels across many bands and ease of system operation and maintenance.The communication of all channels in the tunnel shall be independent, simultaneous and failure-free. 32.2.1.1 System details for Tunnel communication: (i) Master unit: The Master Unit is used to convert signals from RF to light when fibre fed repeaters is used at the remote end of the optical link. Master Unit shall be used in more than 500 meters lengths tunnels. Master Unit system may consist of following sub-system: (a) Channelized VHF Simplex Off-Air Repeater and VHF Simplex Optical Master Unit. (b) GSM-R/LTE Off-Air Repeater and GSM-R/LTE Optical Master Unit. (c) Channelized TCAS/ LocoTrol/ TETRA Off-Air Repeater and TCAS/ LocoTrol/ TETRA Optical Master Unit. (ii) Optical remote unit: Optical Remote unit is used at the remote end to convert Optical Signal to RF Signal and then transmit it into Leaky cable in the particular area to cover the tunnel for the wireless communication. It is connected to Master Unit. Optical Remote Units to accept for VHF Simplex, LocoTrol, GSM-R/LTE, TETRA and TCAS. Remote unit are Monitored, Controlled and Alarmed Remotely from the Master Unit over Fibre and Remotely using an Ethernet Modem. Optical Remote unit shall be used to provide coverage in more than 500 meters lengths tunnels. (iii)Off-Air Channelized Repeater: For less than 500 meters Tunnels are to be covered with High Gain Off-Air Channelized Repeaters feeding Dual Radiating Cable Systems. The Repeaters cover VHF Simplex/LocoTrol, GSM-R/LTE, TETRA and TCAS communication per Bore. (iv) Leaky Cable: For Wireless communication (VHF Simplex, LocoTrol, GSM-R/LTE, TCAS and TETRA) inside the tunnel FRLS-0H (Flame retardant Low Smoke Zero Halogen) rated Leaky cable shall be provided to minimize accumulation of smoke inside the tunnel in case of accidental fire. Two 7/8” Leaky Cable shall runs per tunnel tube length for VHF Simplex, LocoTrol, GSM-R/LTE, TCAS and TETRA communication. Indian Railways Telecom Manual - 2021 Page 384  7/8" Leaky Cable is a type of RF coaxial cable which has gaps or slots in its outer conductor to allow the radio signal to leak into or out of the cable along its entire length so the cable functioning as extended antennas. (v) Antenna for system: For Tunnels less than 500 meters, Antenna shall be installed at tunnel site for VHF Simplex, LocoTrol, GSM-R/LTE, TCAS, TETRA etc. For Tunnels more than 500 meters, Antennas shall be installed on a Tower for VHF Simplex, LocoTrol, GSM-R/LTE, TCAS, TETRA etc. The wireless system and tower with antenna to be installed should have the SACFA clearance as applicable. (vi) Optic Fibre cable: Master Unit at Base station shall be connected to the tunnel optical remote unit through Fibre Junction Box. Video Surveillance System and PA Systems shall also be connected through same Optic Fibre system. (vii) Power supply unit for Master unit, Optical Remote unit/Repeater in Tunnels: For Tunnel Communication, power supply unit with battery backup (230VAC 50Hz or -48 VDC) for Master Unit, Optical Remote unit/Repeaters should be required. (viii) Fibre Junction Box: Fibre Junction box is required for more than 500 meters tunnel lengths. (ix) Optic Fibre & Copper Cable: Optic Fibre & Copper Cable ring should be provided in the tunnel to connect various facilities like PA system, CCTV cameras, etc. Cables (OFC,Quad etc) should be laid in PVC/DWC pipes. 32.2.1.2 Tunnel communication diagram for different lengths of tunnels: (i) Tunnel communication for less than 500 mtrs. lengths: Indian Railways Telecom Manual - 2021 Page 385  (ii) Tunnel communication for more than 500 mtrs. to 5 Km lengths: Indian Railways Telecom Manual - 2021 Page 386  (iii) Tunnel communication for more than 5 Km lengths: 32.2.2 Emergency Telephone: It should be recommended that Emergency Telephone should be installed at the key point in tunnel-cross passages, on escape walkways, on tunnel walls at every 250 meters and shafts. Telephone should be able to function properly and work in the tunnel environment with a potentially high noise and poor light. It is recommended that they should be installed with a sound hood to avoid noise- affecting conversation. Emergency Telephone should be linked to the existing Emergency Control communication system and terminated at the Divisional Control Room. 32.2.3 Public Addressing System: A Public address system shall be provided to inform/warn maintenance and service staff and give instructions to people in abnormal conditions during incident. Therefore loudspeakers shall be installed every 100 m in the tunnel. PA System should be installed at more than 500 meters Tunnel lengths. 32.2.4 Hotline Telephone: Hotline Telephone Services should be extended to Tunnel Maintenance Boxes. These shall be connected to Central Tunnel Control Room/Divisional Control Room.Regular Railway Telephone Services should be extended to Tunnel Maintenance Boxes at appropriate locations. These Railway phones shall be connected to Divisional Railway Telephone Exchange. 32.2.5 Control and Monitoring System: Indian Railways Telecom Manual - 2021 Page 387  IP based Video Surveillance System shall be provided inside tunnels to ensure that there are no blank spots over the tunnels. The camera should perform well in low light scenario inside the tunnels. All the camera feed shall be transferred to the Tunnel Control Center/Divisional Control Room for viewing, recording and monitoring of tunnels through cameras. 32.3 Maintenance of system: (i) Transmitting frequency and power of the system are to be checked once in a month. Normally these measurements are done by the system internally and can be checked through PC/Laptop connected with Master Unit. (ii) Power Supply System: (a) Input and output voltage & currents-Weekly (b) Specific gravity of each cell - weekly (iii) Antenna system along with Radiating cable and connectors: Antenna system at Master location and leaky cable connections inside the tunnels are physically checked weekly basis for any damage or break down. (iv) On weekly basis check the Master unit for any fault alarm(s). If some fault alarms are noticed, connect the Laptop/PC and pinpoint the actual fault for rectification. (v) Emergency Communication (EC) socket-Weekly (vi) Hotline Telephone Services & Regular Railway Telephone- Monthly (vii) Integrated Digital PA System -Monthly (viii) Video Surveillance System- Monthly 32.4 Inspection: All Systems and communication media installed inside the tunnels must be inspected every month by SSE/JE/TELE. 32.5 Failure report: (i) System’s failure must be reported to the controlling officer daily in the morning. (ii) Monthly statement of a failure must be reported in the PCDO to Headquarter. 32.6 Tools and plant required for maintenance of equipment: (i) Optical power meter (ii) Hydrometer Indian Railways Telecom Manual - 2021 Page 388  (iii) Digital Multimeter (iv) Line Tester (vi) Fibre splicing machine (vii) Basic tools like screw drivers and spanner sets (viii) Three handheld radios programmed with the working frequencies (ix) Reference screen shot prepared when the complete system is in satisfactory working condition. (x) A Laptop (xi) Connecting cables supplied along with system. -x-x-x- Indian Railways Telecom Manual - 2021 Page 389