Optical Fibre Communication for Indian Railways

• Optical Fibre Communication System is the backbone of Indian Railways' communication needs.

Communication Types Supported

• Control Communication with emergency communication
• Administrative voice and data communication
• Mobile Train Radio Communication
• IP networks carrying IT applications and internet/intranet services
• Modern signalling applications

Optical Fibre System Guidelines

• Utilize a 24/48 Fibres Optical Fibre Cable as per the newest RDSO specification with 6 Quad Jelly Filled Quad cable that also meets new RDSO specifications.
• Cables should be laid in HDPE pipes via the blowing method, dedicating one fibre pair for communication.
• Reserve a second fibre pair as backup.
• Remaining fibres are transferred to Railtel for commercial use; some may be reclaimed if needed.
• IP-MPLS network deployment for both short and long haul needs will include redundant equipment.
• Short Haul Communication uses STM-1 with Primary Digital Multiplexers (PDMUX).
• A VOIP system for Control Communication will work on existing STM, with plans to shift to IP MPLS.
• Long haul communication is currently fulfilled using Railtel’s network.

System Design Elements

• Location of optic fibre stations/nodes
• Optical loss budget between adjacent nodes
• System capacity to meet current and future needs
• System availability and reliability
• Power supply system design for each station/node
• Preparation of an estimate

Equipment Room Location - General requirements

• The equipment room locations requirements are at stations and level crossings
• The considerations in para 13.2.2 are important when fixing equipment rooms

Considerations for Existing Buildings

• Scanning of the building is necessary
• Existing buildings for optic fibre equipment rooms is subject to considerations
• The cost for room modification must be significantly less than constructing new rooms.
• The area must accommodate Section-III layout.
• Building proximity to the cable route is important to minimize cable length.
• Availability of preferred standby power
• The site elevation must exceed the highest flood level.
• Limited track crossings
• Optimal location within or near a station building

Requirements for New Wayside Buildings

• The New OFC building site must be close to the station building
• No restaurants or tea stalls nearby
• Even-level site
• Avoidance of mid-track locations
• Positioning on the same side as the optic fibre cable
• Site accessibility via road
• Adequate space for equipment storage
• Tower construction space for train radio communication
• The distance to join the copper cable for the OFC room is minimal
• Proximity to the ASM’s (Assistant Station Manager) Office for equipment security

Control Room Location

• Adherence to all requirements EXCEPT location; OFC (Optical Fiber Cable) room to integrate within the control office complex.

Building Construction Requirements for OFC (Optical Fibre Cable) Rooms

• OFC rooms must comply with drawing No. RDSO/TCDO/COP-1(a) for wayside locations
• Main control stations and critical nodes buildings shall be as per Drawing No. RDSO/TCDO/ COP-2(a).
• Buildings should be made of bricks and concrete, with sturdy doors and dust-proof sealing to prevent intrusion
• Cable pit should be 1.25m deep with two 100mm diameter RCC pipes for OFC and quad cables
• RCC pipes should be laid 2m away from the cable pit with a slope for smoother cable entry
• RCC pipe ends should be sealed with Plaster of Paris
• Provide uninterrupted power and backup with remote monitoring; conceal electrical wiring
• Use oil distemper that lasts 10–12 years to prevent distempering
• Use PVC tiles or synthetic flooring in equipment rooms
• Exhaust fans in battery rooms must be shielded from rain with wire mesh to keep out pests; use acid-proof tiles
• Install air conditioning units in critical OFC backbone locations with high ambient temperatures
• Ventilation shown in Drawing No. RDSO/TCDO/COP-1(a) & 2(a) should be installed elsewhere.
• Windows and ventilators must have wire mesh to prevent theft and rodents
• Earthing connections should be near the OFC room

Equipment Layout Specifications

• OFC equipment layout at wayside stations and control offices must match Drawing Nos. RDSO/TCDO/COP-03(a) and RDSO/TCDO/COP-04(a).
• Equipment should fit into standard 19-inch racks.
• Battery wiring is to be placed inside appropriately sized and supported PVC channels.

Optic Fibre Cable Route Preliminary Survey

• Finalize optical fibre cable route drawing as part of execution and planning
• Survey main tasks: route selection, drop/insert location number, size and length assessment.
• Working out circuit provision requirements, assessing tool/plant needs based on soil, roads, and territory.
• Identifying special section problems like soil type, embankments, water-logged areas, bridge types, major yards.
• Gathering existing telecommunications details, electrification needs, and creating tap diagrams.
• Estimate track crossing numbers with other protective needs
• Cables will be laid far from newly constructed tracks
• Avoiding embankment toe proximity with the cultivated fields is important
• Avoiding burrow pits and flood zones while maintaining cable integrity
• Avoiding soil from coal, cinders and ash
• Steer clear of soil with acids, decomposable matter, and electrolytes which promote bacterial activity.
• Dodge areas near industries chemically discharging active affluent.
• Avoiding large rock cuttings, thick jungles, existing cable routes and areas difficult to approach
• Careful cable hut approach decisions to avoid construction zones
• Determining soil composition for corrosion impact and protection requirements
• The cable circuit chart and tapping diagrams are setup to work out the circuits required
• Working out transport vehicle requirements
• Avoid areas prone to earthwork or structural changes

Route Plan and Diagrams

• The cable route plan indicates the route's relation to the main line track center.
• Indicate the route along the DN or UP main line for double line sections.
• Indicate if it's on both sides or the right side for single line sections.
• Prepare a tapping diagram indicating the tappings of various circuits and other permanent structure routes for easy route identification.

Cable Route Selection

• Account for terrain's variations to enhance cable route advantages, cautioning against frequent track crossings.

Route Considerations

• Avoid underground structures such as signalling cables, power cables, and pipelines.
• Avoid cable laying on the side of drains in built-up areas because it is generally difficult task
• Opt for cable routes away from railway signalling cables in station yards
• Cable routes should go through small culvert beds through HDD to avoid water accumulation and take place over the culverts
• Remove termites/rodents infected areas
• Main line sides has preference over coastal sides

Detailed Cable Route Survey

• Detailed surveys closer study existing telecommunications, work out material needs, finalize drawings and site plans, examine collected details, and make essential modifications
• Closely inspect suggested cable route in addition to prepared cable route plans.
• Identifying location for cable hut buildings in addition to preparation of site plans.
• Work with areas needed to load/unload cable drums along with siding area which is needed for EMTs as part of project needs.
• Calculate particular cable needs regarding long girder spans.
• Create material schedule in relation to different protection plans.
• Organize separate telephone connection in any cable
• Study sections with problems and seek solutions
• Horizontal scale: 10 cm=1 km, 5 km chart
• Mark ASM's offices, cabins, OHE switching posts, etc. with location and chainage
• Write the km post number every 10 cm and include OHE chainage.
• The station name must match the Station Master's office location.
• Mark culvert serial numbers and lengths, the bridges, and level crossings onto the cable route plan’s ‘Track Line’.

Guidelines for Finalization

• A latest OHE survey plan must be added to enter the relevant changes and chains all on ‘5 KM charts’.
• Important areas for cable route are ‘special trains’ including big yards, parallel courses diversion- obstruction and cutting require 30m of steel or chain

Guideline Steps

• Determine any ' special terrains' per para and longitudinal measurement requirements
• The remaining parts of the route as ' straight runs'.
• The actual chain isn't important, '5 km charts' should have chainages in the OHE Plan.
• Begin the cable from the control office through a 30m steel tape up to the main area and reckon the route distances with use of the OHE Plan.
• Gauge the separation distance from the reference trach on ' straight runs'
• The separation distance can also to be compared to permanent structure on sites where ‘special terrains’

Additional Guidelines

• The OHE masts must have at least 5.75 metres separation to the cable and a 1 m shall be kept that the OFC be set on an HDPE pipe.
• Move along track with push Trolley on long and ' straight Runs' .
• Measure how protective gear shall be arranged onto bridges over the culverts, arch and girder bridges, level crossings and OHE posts areas
• The survey must visit cabins, and SM’s offices etc to obtain RE details to traction, loco, and emergency control. As well to Electrical department sub- section and traction posts with socket posts not to extend 1 to 1.2 km.

Cable Length

• The cables must enter all buildings based on Drawing Number RDSO/TCDO/COP-18
• The route must factor into the Cable length basis - contour, track length, bridge length, at each major steel or short bridge and cable hits.

Handling Storage

• To avoid cable damages the following shall apply when handling.
• Cable drums shall be released upon layers to avoid sinking
• Do not stack drums on flat side with its stability shall be taken
• Cable drums are to be stored so that the drums are easy to move with the site away from the site.

Rotation on unloading

• When the cable is being unloaded, the drums are to be drum shall always be ‘ROTATED IN THE DIRECTION OF AN ARROW WHICH IS MARKED ON THE SIDE BOARDS OF THE DRUMS, sometimes 'ROLL THIS WAY'.
• Protective cable needs to be assured that it is not moved across any object, or protective batten.

Steps for handling

• Drums need to be checked and transit. The cable must have their batten fixed until installations.
• When carrying a drums of vehicle, drums are is shall never drop on GOUND to prevent impact.
• Use forklift with fork which will be on weight with flanges.

Safety for Cable

• It is Important during to make sure that there is no damage to end cap on any HDPE PIPES
• All protection should maintain under stages including effectively seal it.

Multiple Choice Questions

1. Which of the following types of communication are supported by the Optical Fibre Communication System for Indian Railways? a) Smoke signals b) Control Communication with emergency communication c) Telegraph d) Carrier pigeons

2. What is the recommended fibre configuration for the Optical Fibre System as per the guidelines? a) 12/24 Fibres Optical Fibre Cable b) 6 Quad Jelly Filled Quad cable c) 24/48 Fibres Optical Fibre Cable with 6 Quad Jelly Filled Quad cable d) Any type of fibre optic cable

3. What is the typical depth of the cable pit near the OFC room? a) 0.75 m b) 1.00 m c) 1.25 m d) 1.50 m

4. According to Section IV, the equipment in the OFC room should be accommodated in: a) Custom-built enclosures b) Standard 19” size racks c) Wall-mounted shelves d) Any available space

5. What is the minimum distance that should be maintained between OHE masts and the cable? a) 3.75 m b) 4.75 m c) 5.75 m d) 6.75 m