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CHAPTER XIII OPTICAL FIBRE COMMUNICATION SYSTEM SECTION – I PLANNING AND SYSTEM DESIGN 13.1.1. Optical Fibre Communication System is the backbone system for all...
CHAPTER XIII OPTICAL FIBRE COMMUNICATION SYSTEM SECTION – I PLANNING AND SYSTEM DESIGN 13.1.1. Optical Fibre Communication System is the backbone system for all types of communication needs of Indian railways such as; (a) Control Communication with emergency communication (b) Administrative voice and data communication. (c) Mobile Train Radio Communication. (d) Various IP networks carrying IT applications and internet/intranet services (e) Modern signalling applications 13.1.2. Guidelines for use of Optical Fibre System. Following Optical Fibre system configuration should be used. - 24/48 Fibres Optical Fibre Cable as per latest RDSO specification with 6 Quad Jelly Filled Quad cable as per latest RDSO specification. All Optical Fibre Cable should be laid in HDPE pipe using blowing method. one pair of fibres shall be used for communication. For back up, a second pair of Fibre shall be kept reserved to be used in case any of the working fibre gets defective/faulty. Rest of the fibres have been transferred to M/s Railtel for commercial revenue realisation. If required some of the transferred fibres may be taken back from Railtel. - In all future works, IP-MPLS network shall be installed for both short haul and long haul communication requirements keeping provisions of redundant equipment and routes. - Short Haul Communication is presently on STM-1 System with Primary Digital Multiplexers (PDMUX). For Control Communication application, VOIP system shall be used which shall work on existing STM network and in future it will be shifted to IP MPLS network. Long haul communication requirements are being met through Railtel’s network on mutually agreed terms. 13.1.3. System design for the above types of communication are as under:- (a) Location of optic fibre stations/nodes (b) Optical loss budget between adjacent nodes (c) Requirement of system capacity to meet present and future needs. (d) Availability/Reliability of the system. (e) Design of power supply system for each station/node. (f) Preparation of an estimate. ********** Indian Railways Telecom Manual - 2021 Page 117 SECTION – II LOCATION OF OPTIC FIBRE EQUIPMENT ROOMS 13.2.1. GENERAL : 13.2.1.1. The system design and the planning covered under section I lists out the requirements of optic fibre equipment locations along the route such as station, level crossing, etc. 13.2.1.2. For fixing the exact location of the optic fibre equipment room at such arrived locations, the following considerations at para 13.2.2 need to be kept in view. 13.2.2. SURVEY OF EXISTING BUILDING : 13.2.2.1. In order to optimize the existing infrastructure facilities and to ensure cost effective project execution, it is necessary to scan the building at the station where optic fibre equipment room could be provided as per system design. However, the recourse to utilize existing building should be made subject to the following :- (a) Expenditure on addition/alteration necessary to make the room suitable for housing the optic fibre equipment shall be much less than cost of construction of new rooms at the appropriate site for Optic fibre equipment. (b) The total area is sufficient to accommodate the layout as per Section- III. (c) The location of the building is close to the cable route to avoid extra cable length. (d) Power supply is available and preferably standby power is also there. (e) The site shall be higher than the highest flood level of that place. (f) It shall not involve many track crossings. (g) It should be preferably in same station building/ close to the station building 13.2.2.2. In case the existing building for wayside location is not available, a new optic fibre equipment building for wayside location shall be decided with the following considerations; New OFC building site should be close to the station building: (a) Restaurants, tea stalls should not be close by. (b) Site should be at an even level. (c) Site in between track to be avoided. (d) Preferably the site should be on the same side of the track as the route of optic fibre cable. (e) There is road access to the site. (f) Sufficient open space is available for – - Storage of the equipment Indian Railways Telecom Manual - 2021 Page 118 - Construction of tower for train radio communication. (g) The distance of copper cable required to join the OFC room for local services should be minimum. (h) For reasons of security of equipment, it should be close to the ASM’s Office. 13.2.3. FOR CONTROL ROOM LOCATION 13.2.3.1 All the above requirements are to be met except that of the location OFC room shall be a part of the control office complex. ********** Indian Railways Telecom Manual - 2021 Page 119 SECTION – III BUILDING LAYOUT 13.3.1 The wayside OFC room shall be as per drawing No. RDSO/TCDO/COP-1(a). 13.3.2 The building for the main control station and Critical Nodes shall be as per Drawing No. RDSO/TCDO/ COP-2(a). 13.3.3 Following is to be ensured for the building: 13.3.3.1 It should be made preferably of bricks and concrete. The front door shall be sturdy to prevent the intrusion by antisocial elements and sealing shall be such that it prevents ingress of dust also. 13.3.3.2 Cable pit near OFC room shall have depth of 1.25 m. Two RCC pipes of 100 mm dia each will be provided separately for OFC and quad cable. The pipes shall be laid up to 2 m length away from the cable pit outside with suitable slope in such a way that smoother entry of cable inside the cable pit is obtained. One end of the RCC pipe will open at the bottom of the cable pit in one of the side walls and the other end will extend to 2m inside the trench with suitable slope. The cable trench will be made deeper at the entry. End of RCC pipes should be sealed with Plaster of Paris. 13.3.3.3 AT Power supply and standby arrangement with remote monitoring of supply should be provided. Preferably the wiring for electrical fittings, plug points, etc. should be concealed type. 13.3.3.4 To avoid frequent distempering, Oil distemper which may last for 10 to 12 years to be provided. 13.3.3.5 Floor shall be provided with PVC tiles or any other suitable synthetic covering in the equipment room. 13.3.3.6 In the battery room, the exhaust fan shall have a rain protection shed and hole covered with wire mesh to avoid entry of birds, insects, etc. Acid proof tiles should be used for the battery room. 13.3.3.7 Air Conditioning should be provided in all critical OFC backbone locations where ambient temperature is normally on the higher side. In other locations, Ventilation arrangements should be provided as shown in Drawing No. RDSO/TCDO/COP-1(a) & 2(a). 13.3.3.8 Windows and Ventilators shall be provided with suitable wire mesh and grill arrangement to prevent theft and entry of rodents etc. 13.3.3.9 Earthing arrangements should be provided near the OFC room. ********* Indian Railways Telecom Manual - 2021 Page 120 SECTION IV LAYOUT OF EQUIPMENT 13.4.1 The layout of equipment in the OFC room at wayside stations and control office shall be as per Drawing Nos. RDSO/TCDO/COP-03(a) and RDSO/TCDO/COP-04(a) respectively. 13.4.2 The equipments shall be accommodated in standard 19” size racks 13.4.3 The wiring from battery to the location of equipment shall be inside PVC channels suitable size and suitably supported all along length. *********** Indian Railways Telecom Manual - 2021 Page 121 SECTION V PRELIMINARY SURVEY OF OPTIC FIBRE CABLE ROUTE Preliminary survey shall be carried out for finalizing the drawing for the route of optical fibre cable as a part of project planning and execution. Following main items of work shall constitute the survey. 13.5.1 Selecting the route in general. 13.5.2 Deciding the number of drop and insert locations. 13.5.3 Deciding the size and assessing the length of cable required. 13.5.4 Working out the requirement of circuits which are to be provided in the cable. 13.5.5 Working out the requirements of heavy tools and plants depending upon the nature of the territory, availability of roads along the tracks, etc. 13.5.6 Assessing the special problems of the section such as type of soil, long cuttings, new embankments, water logged areas, types of major bridges, major yards. 13.5.7 Collecting details of the existing telecommunication facilities and the additional requirements due to electrification and preparing tentative tapping diagrams. 13.5.8 Assessing the number of track crossings and other protective works required to be done. 13.5.9 Avoiding laying of cable too close to a newly laid track, as far as possible. 13.5.10 Avoiding the toe of the embankment adjacent to the cultivated fields. 13.5.11 Avoiding burrow pits and areas prone to waterlogging. 13.5.12 Avoiding soil made up of cinders, coal ashes, etc. 13.5.13 Avoiding heavily fertilized soils containing acids, electrolytes and decomposable organic materials promoting bacterial activity. 13.5.14 Avoiding proximity to chemical, paper and such other industries which discharge chemically active affluent. Indian Railways Telecom Manual - 2021 Page 122 13.5.15 Avoiding large rock cuttings, thick jungles, routes of existing cables and areas difficult to approach. 13.5.16 Deciding carefully the cable route approaches to cable huts to avoid built up areas including those areas where building, etc. are likely to come up in future. 13.5.17 Determining composition of the soil which may affect corrosion, etc. on the cable and special protection required for cable. 13.5.18 Working out the requirement of the various circuits to be provided in the cables along with the cable circuit chart and tapping diagrams. 13.5.19 Working out requirement of transport vehicles. for the execution of the work. 13.5.20 Avoiding on the side of the alignment which is likely to be affected due to addition/alteration of earth work/supply structures (such as construction of double lane, shifting of alignment of the existing track etc.) 13.5.21 Preparation of cable route plan and tapping diagrams. The cable route plan should indicate the route with respect to the main line centre of track, that is, whether the route along the DN main line or UP main line in case of double line sections and whether it is on both side or right side of the main line when facing a particular direction in case of single line section. A tentative tapping diagram should be prepared for the section indicating the tappings of various circuits. In addition to above, the cable route plan should also indicate the route with respect to other available permanent structures for easy identification of route. 13.5.22 Selection of the Cable Route. Generally the terrain conditions on the two sides of the track vary to such an extent as the cable route on one side of the track has a distinct advantage over that on the other side. While operating on the principle, it should be borne in mind that frequent track crossings are not desirable. In addition to the above, the following also need consideration:- 13.5.22.1 Avoiding underground structures, signalling cables, power cables, pipe lines, etc. 13.5.22.2 Avoiding the laying of cable on the side of the drains in built up areas which is generally difficult. Indian Railways Telecom Manual - 2021 Page 123 13.5.22.3 Selecting the cable route as far as possible on the opposite side where Railway signalling cables already exist in station yards, etc. 13.5.22.4 Taking the cable route preferably through the bed of small culverts preferably through HDD method where water does not accumulate instead of taking it over the culverts. 13.5.22.5 Avoiding termites/rodents infected areas. 13.5.22.6 Preference at the side of the main line away from the coastal side. ********** Indian Railways Telecom Manual - 2021 Page 124 SECTION – VI DETAILED SURVEY AND FINALISATION OF THE ROUTE PLAN OF OPTIC FIBRE CABLE Detailed Cable Route Survey: 13.6.1 Purpose: The purpose of the detailed survey is to undertake closer study of various existing telecommunication facilities to work out exact requirement of materials required for different items of work to finalize all the drawings and site plans required for the execution of work as also to examine the details collected during preliminary survey and to offer necessary changes/modifications, if any. 13.6.2 Main items of work: The following are the main items of work which should constitute the detailed survey: i) Closely examining the proposed cable route and prepared cable route plans. ii) Siting of cable hut buildings and preparation of site plans. iii) Siting and preparation of site plans for buildings required for the execution of the work, as offices at different stations, store godowns, etc. iv) Siting of areas for loading/unloading of cable drums and siding facilities for the EMTs (Engineering Materials Trains) for the project. v) Estimating of requirement of special cable lengths for long girder bridges. vi) Preparation of the material schedule required for different protective works. vii) Arranging isolated telephone circuits to be provided in the cable. viii) Investigation on special problems, if any, of the section and finding out proposed solutions thereof. 13.6.3 Procedure: For the preparation of the main cable route plan, “5 Km charts” should be prepared which covers a length of 5 Km of the route. The horizontal scale is 10 cm = 1 Km. Based on the OHE location survey plan, the locations of ASM’s office, cabins, OHE switching posts, etc. should be marked on the charts. The name of the location should be put in the ‘LOC’ column and the chainage in the ‘CH’ column. At every 10cm the km post number should be written and its exact equivalent chainage as per OHE survey plan entered in the ‘CH’ column. The equivalent chainage is required for working out the length of the cable Indian Railways Telecom Manual - 2021 Page 125 required. The name of the station should be shown against the location of the Station Master’s office. Based on the OHE survey, the serial number and the length of culverts, bridges and level crossing shall be marked on the ‘Track Line’ of the cable route plan. The survey party should be supplied with prints of ‘5 km charts’ with the above details entered for enabling them to mark the route, and other details after surveying. The following are the guidelines for finalizing the route and preparation of the cable route plan:- i) Prepare the ‘5 km charts’ as explained above and collect the latest copy of approved OHE survey plan to enter the relevant chainages and details in the ‘5 km charts’. ii) Actual measurement by 30m steel tape or chain along the route is necessary only in case of important locations to be termed as ‘special terrains’ for example, approach to long bridges, big yard, sharp diversions in the cable route from its parallel course along the main Railway tracks due to obstruction, cuttings, etc. iii) Inspect and decide the portions of route falling in the category of ‘special terrains’ stated in para (ii) above, i.e. where actual longitudinal measurement is necessary. iv) The remaining portions of the route, i.e. other than the portion decided as ‘special terrain’ as per para (ii) above are to be termed as ‘straight runs’. Actual chaining along the route is not necessary for such ‘straight runs’ and these can be marked on the ‘5 km charts’ by taking chainages from the OHE plan. v) The cable route shall be started from the control office. At that measurement along the route should be done by means of a 30m steel tape for a few drum lengths up to a convenient point along the main line where from the distances along the route may be reckoned from the OHE plan. vi) Actual measurements of the separation distance from the centre line of the reference track (a reference track shall always be the main line) is essential in case of ‘special terrains’ on ‘straight runs’ this measurement shall be made where necessary. In case of ‘special terrains’ the separation distance at some points on the route may also have to be reckoned from some other permanent structures depending upon the site conditions. vii) As a rule, a minimum distance of 5.75 m should be maintained between the OHE masts and the cable. In yards, etc. where Indian Railways Telecom Manual - 2021 Page 126 observance of this rule may be difficult, a minimum distance of 1 m shall be maintained ensuring that OFC is laid in HDPE pipe. viii) The route shall be decided by walking along the track on long stretches of ‘straight runs’ a push trolley moving slowly may be used. The trolley shall be on the track close to the proposed route. ix) Actual measurement shall be made for the protective works required for the cable passing over the culverts under tracks, over long girder bridges, arch bridges, level crossings, rocky areas, under the bed of culverts and near OHE switching posts, etc. x) The survey party shall visit each location such as cabins, SM’s offices, loco sheds, pump houses, gate lodge, etc. and verify the details collected during the preliminary survey of all the existing telecommunication facilities to be provided due to RE such as tappings on traction power control, traction loco control, remote control and emergency control circuits. For emergency control circuits in addition to the general tappings to be provided at every 1 to 1.2 km. The details of tappings specifically required by the Electrical Engineering Department for their switching posts such as sub-sectioning posts, sectioning posts, traction sub-stations and isolated locations, etc. shall be collected well in time. The exact location of the various tappings on the emergency control shall then be worked out taking into consideration the tappings to be essentially provided at specific locations for the Electrical Engineering Department so as to ensure that the distance between the consecutive emergency socket posts does not exceed 1 to 1.2 km. The position of each tapping shall thus be finalized and a final tapping diagram prepared. 13.6.4 CABLE LENGTH : 13.6.4.1 Cable entry in the cabin and other buildings shall be as per Drawing Number RDSO/TCDO/COP-18. 13.6.4.2 The cable length shall be worked out on the following basis : (a) Route length as per actual measurement plus contour allowance of 2.5%. (b) Extra length for track crossing including 2.5 meters loop on each side. (c) 10 meters extra length on approach/crossing of the bridges and culverts on each side as per measurement in the detailed survey. (d) 5 meters of cable to be kept on either side of major steel bridges and 2.5 meters of cable on short bridges. (e) At every joint a loop of 10 meters on either side shall be kept. (f) In cable huts a loop of 10 meters in the cable pit shall be kept. Indian Railways Telecom Manual - 2021 Page 127 13.6.4.3 Special lengths for long girder bridges. For long girder bridges, special length of cable may be required. This is to avoid the location of a joint on such bridges, on slopes leading to bridge abutments and on top of deep cuttings, etc. These details regarding the approaches to the bridges shall be worked out. 13.6.5 Materials required for protective works. 13.6.5.1 For crossing masonry platform, and at culverts, level crossings and road crossings etc. special protection for cable is required. 13.6.5.2 Actual measurement should be made for the length at which special protection is necessary and requirement of materials for the protection should be worked out. The requirement of material based on the actual measurement should be shown in cable route plan at the appropriate place. ********** Indian Railways Telecom Manual - 2021 Page 128 SECTION – VII CABLE HANDLING TECHNIQUE FOR STOCKING & TRANSPORTATION OF OPTIC FIBRE CABLE 13.7.1 GENERAL: The following practices are to be followed to prevent damages or deterioration of the cable during handling and storage. 13.7.2 The cable drums stored in open shall be kept on a strong surface such as released sleepers to prevent sinking. The drums shall not be stacked on its flat side and also suitable stoppers shall be placed properly for its stability. 13.7.3 The cable drums shall be stored in a manner allowing easy access for lifting and moving and the drums shall be stored away from other construction activities. 13.7.4 When rolling the cable drum either for unloading or transportation to cable laying site, the 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’ ARROW IS INDICATED ON THE DRUM FLANGE. 13.7.5 The drums shall not be rolled over objects that could cause damage to the protective battens or the cable. 13.7.6 After transit, the drums shall be inspected for damage such as broken battens and where possible, the outer layers of the cable should be inspected. 13.7.7 The cable drums shall always be kept upright with the cable ends securely tied to prevent unwrapping. All battens or coverings shall be left in a place until the cable is unrolled from the drums during installation. 13.7.8 UNLOADING OF CABLE DRUMS AT PLACE OF STORAGE OR AT CABLE LAYOUT LOCATION : 13.7.9 UNLOADING OF CABLE DRUMS (a) When unloading of a drum is carried out from a vehicle, the drums SHALL NOT BE DROPPED ON THE GROUND directly to avoid irreparable damages to the cable due to impact. (b) Steps for unloading : i) Unload the drums with fork lift truck with forks enough to take full width of the drum so that the weight is born by both the flanges. OR Indian Railways Telecom Manual - 2021 Page 129 ii) The cable drum may be lifted by a suitable crane. For this purpose, a suitable size spindle shall be placed through a central hole and double ended shall be attached to the spindle. The spindle shall be equipped with a stopper of such a length that will not cause damage. 13.7.10 LOADING OF CABLE DRUMS Same precautions as for unloading are to be followed. 13.7.11 SEALING OF CABLE and HDPE PIPE END During all stages of storage/use, it is essential that the end of the cable and HDPE pipe are effectively sealed end cap. Failure to effectively seal may result in water entry in the cable and making it unfit for the use. ********** Indian Railways Telecom Manual - 2021 Page 130 SECTION – VIII LAYING OF DUCT IN TRENCHES AND BLOWING/PULLING OF CABLES IN DUCT 13.8.1 WORK FLOW DIAGRAM : The major steps for cable laying in trenches are shown below. Before commencing each step, be sure to check how far the work of preceding step has been completed and how well the preparations for the work of subsequent step have been made. Indian Railways Telecom Manual - 2021 Page 131 13.8.2 CABLE INSTALLATION AND TRENCHES – GENERAL Armoured fibre optic cable shall be blown into duct laid and suitably aligned in the trench. Only in unavoidable conditions due to terrain/approach, pulling of cable in duct may be permitted in small subsections. The trenching and laying method is dependent on both ground configuration and nature of the soil at site. The duct shall conform to the latest Specification of TEC/RDSO. From specifications and drawings, ascertain the route of the cable, requirement of the materials, labour and work period, etc. 13.8.3 PREPARATION OF MATERIALS , TOOLS AND EQUIPMENTS (a) Check that all tools and equipment for installation detailed in Section XI are ready at site. (b) Check that the required quantity and type of material for laying of cable in trenches are ready at site. (c) Take care to keep the tools metal fittings equipment in a warehouse to prevent being stolen/lost. (d) In case, materials have to be kept on the road care must be taken to ensure that traffic is not hampered and no inconvenience is caused to the public. (e) Special attention must be paid to avoid keeping material on or around the fire plug or hydrants sewage duct. In case, it becomes unavoidable, use across such locations. 13.8.4 TEST DIGGING Before cable installation, inspect the route with reference to the approved plans and the specification and ensure that there are no obstacles in the route. Conduct test digging to ascertain the existing facilities and record the position and depth of cable to be installed as well as any existing underground cable or water pipes etc. 13.8.5 INSPECTION (a) Check the cable installation position shown in the cable route plan vis- à-vis the actual condition site. (b) Determine the cable jointing points and curving points from the offset shown on the cable route plan and measure the distance between them and the surplus lengths. 13.8.6 TRENCHING 13.8.6.1 Traffic Safety : The telecom cables should normally be laid within 1 metre inside the Railway boundary and far away from traffic movement. At the site of cable Indian Railways Telecom Manual - 2021 Page 132 installation, take the following measures for traffic safety if trenching is unavoidable near places where traffic movement is involved; (a) Provide ‘WORK IN PROGRESS” plate wherever necessary at both ends of the site and provide signages and sufficient lighting during night. (b) Wherever necessary, provide suitable fences at the end and side of the trenches to keep vehicles and pedestrians away. At night, use warning lamps or equivalent at adequate distances. 13.8.6.2 Burying depth of duct (a) The standard depth of duct should be such as to ensure the standard depth of cable which are defined in drawings for various types of locations/civil structures. (b) The depth of the duct shall be enough to prevent natural, artificial obstacles and damages. The standard depth must not be less than the specified. Sharp depth variations to be avoided to prevent macro bending of the OFC affecting performance. (c) In case it is a rocky area, the depth may be reduced by using the concrete protection. 13.8.6.3 The standard trench : (a) The standard trenches are as follows for different conditions: - Trench for laying duct for optic fibre cable (typical RDSO/ TCDO/COP-6(a)). - Trench for laying duct for optic fibre cable with 6 quad cable and PIJF cable in the same trench (typical RDSO/TCDO/COP-8(a)). - Trench on embankment for duct for optic fibre cable (RDSO/TCDO/COP-9(a)). - The trenching in the rocky area for duct for optic fibre cable (typically RDSO/TCDO/COP-10). 13.8.6.4 Excavation : The excavation for trenching may be made either manually or by mechanical means. (a) Manual excavation : - The depth of the trench may be measured by a rule made of pipes as per RDSO/TCDO/COP-11(a) - When the surface of the ground where the trench is dug is slanting or uneven, the depth is measured with respect to lower edge. Indian Railways Telecom Manual - 2021 Page 133 (b) Machine excavation : Excavation of trench can also be done mechanically by:- - Loading backhoe equipped with excavating bucket, cleaning bucket, back filling blade and lifting tackle. This backhoe may be suitably used for lifting cable drum equipped suitably. - Other mechanical excavation with mechanical fittings to trench and excavate. - CATERPILLAR TRACTOR can be used for laying cable along cable route using adjustable ripper having typical preparation of 1.20 meter depth to install cable at 1.2 meter depth. 13.8.6.5 After digging is done to specified depth, the bottom of trench should be levelled by removing the exposed stones or obstacles, etc. 13.8.6.6 A day’s trenching is to be such a length that cable laying and back filling can be finished during the day. This however, would not apply to cases where operation does not hamper the traffic and where cable trenches are not exposed to likely interference/damages. 13.8.7 HANDLING AND LAYING OF DUCT : 13.8.7.1 The coil of duct shall be unloaded by the side of the Railway track from either a crane or by any other suitable means very carefully so as not to cause any damage to the duct. The coils at site shall be protected until they are laid. The duct shall be given the same care in handling as that given to the cable. The coils shall be kept as per the guidelines issued by the manufacturer. The coil shall not be set by jerks but shall be handled slowly and carefully. The walls of the ducts shall not be damaged while moving the coils, if required for unloading. 13.8.7.2 The coil shall normally be unrolled at the same place and the duct carried by workmen near the trench. The coils shall not be dragged in any case. But where the drums/coils of duct have to be moved should always be rolled in the direction of the arrow, otherwise the coils tend to unwind and the same may get battered. In case no such direction of arrow is given see the direction of winding of the coil and the coil should be rolled pointing in the opposite direction in which the upper end is coiled. 13.8.7.3 All care should be taken in handling the coils with a view to ensure safety of the coils but also of the working party handling them. The coil should not be broken by standing in front of the coil but only from side. 13.8.7.4 DUCT LAYING : It is advisable to employ the same people at the same place or job while duct is being laid. Indian Railways Telecom Manual - 2021 Page 134 Before commencement of the laying, inspection of the trench and inspection of protection works should be carried out so as to ensure their conformity with the specification. The trench bottom should be clean, smooth and free of small stones. When the soil contains stone or pieces or rock and therefore cannot be raddled, sieved earth about 10 cm. thick should be used for the bedding on which the duct is being laid. The duct coil should be brought as close to the trench as possible. It should be lifted carefully with the aid of jacks 13.8.7.5 (i) It is customary for the mate to stand in a commanding position where he can view the entire road and shout evenly and call his men to pull. If there is proper synchronization between the mates call in the pulling by the men the duct will leave the coil without difficulty. It is important that the duct shall be pulled with steady and even pulls and there should not be unnecessary twists. Care should be taken to avoid twist as this is likely to damage the duct. When pulling around bends one or two men should be stationed to give the duct the correct bent when it passes. (ii) While laying the duct, we should employ an adequate number of men so that the duct can be conveniently carried by them in both hands without stretched arms. The distance between any two persons carrying the duct shall be two to ten meters depending upon the weight such that the maximum sag of the duct between any two persons is not more than 0.5 meters. (iii) While laying work is in progress one man has to continuously observe the duct along its line in order to determine indentations poles or other damaged parts are apparent. Such damaged parts have to be protected immediately. (iv) The conditions of the duct shall be visually inspected throughout its line and in case damage or defect is noticed, the trench shall be filled up only after ensuring that the damage is not likely to affect the cable. (v) The end of the duct should be sealed with flex to prevent entry of soil before filling back. Adjoining ducts shall be joined by couplers. Duct integrity testing (as per annexure-I) shall be carried out when laying is completed in a block section (8-10 kms). In case the continuity is not achieved the fault shall be localized and rectified by providing HDPE couplers/Compression couplers. 13.8.7.6 Tools necessary for laying Duct is detailed in Section XI to be checked as physically available before starting the Duct laying. For efficient and safe Duct laying, communication may be provided between following points using portable VHF Walkie talkie sets : a. Duct Coil end Indian Railways Telecom Manual - 2021 Page 135 b. Any intermediate manhole/diversion/track crossing through which the Duct will be passed. c. The Supervisor Incharge of the Duct laying. Whenever duct is to be laid in the duct (GI pipe or RCC pipe), suitable lubricant on duct may be used to reduce friction and consequently the tension on the cable. During duct laying care must be taken not to twist duct in any direction. For this purpose, the swivel (rotating hook) shall be attached between pulling line and pulling eye at the end of duct so as to avoid any possible twist during pulling and laying of the cable. In case it is planned to lay the cable in duct by pulling the cable by using a winch; the duct should be provided with a nylon rope for pulling the cable. 13.8.8 PREPARATION FOR PAYING OUT CABLE (a) Check the drum number and length of the cable, etc. (b) Entrust cable drum to the contractor after testing the fibres with OTDR for attenuation and to ensure that no mechanical damage of the fibre exists while handing over the cable to the contractor. (c) Place the cable jack (to support cable drum) on a flat surface. (d) Put cable spindle through drum and adjust cable jacks so that the drum may be 3-5 cm clear from the ground and that the spindle may become horizontal. Remove carefully lags of drum with bar or other means by taking care that no damage to the cable takes place. (e) Pull out nails from lags or bend them so that operation can be done safely. (f) Normally both ends of the cable is provided with cable grip and pulling eye. In case, it is not already provided, fit the cable grip/pulling eye to the swivel and pull the wires by means of shackle. (g) Bending of a fiber optic cable can damage the cable if the radius of the bend is too small. The normal recommendation for fiber optic cable bend radius is the minimum bend radius under tension during pulling is 20 times the diameter of the cable. For armoured OFC used by IR, keeping sufficient safety margin, bending radius under tension during pulling should always be greater than 30 times the diameter of the OFC. Indian Railways Telecom Manual - 2021 Page 136 13.8.9 LAYING OF CABLE BY WINCH This method should be used for smaller lengths only (a) Stretch pulling rope on rollers and fix its end on winch. (b) Use 2-3 tonnes winch and put it near the dug trench. The winch shall be fastened at the back wire to a pile driven into the ground to prevent from moving out of place due to pulling tension. (c) After everything is ready, post workman at winch, cable and using communication, pull slowly into the duct by means of winch. Cable shall be laid under a specified pulling tension bending radius and pulling speed as shown below : (d) DURING ITEM VALUE INSTALLATION PULLING TENSION (1.1 times W )Kg. BENDING RADIUS >30 times D PULLING SPEED Max.15 m/min D – Cable outer dia W – Weight of Cable per Km. in Kg 13.8.10 BLOWING OF OFC CABLE Optical fibre cable will be blown into pre-lubricated HDPE duct laid with the help of a compressor and blowing equipment. Before blowing of OFC, duct integrity testing (as per annexure-I) on laid HDPE duct should be carried out. The blowing method involves feeding of optical fibre cable into the duct with the help of consistent high pressure airflow, equally distributed along the entire cable throughout the duct. The following steps may be adopted for safe blowing of OFC : i) Position the compressor and blowing machine at blowing pit C for location A & E shown below. ii) Put the cable drum on cable wheel and blow the OFC towards pit A. A pusher equipment may be placed at B if required. Indian Railways Telecom Manual - 2021 Page 137 iii) When the cable reaches pit A and coil of 10 - 15m of OFC should be kept in pit A. Then seal the duct end at A with the sealing plug. iv) Uncoil the cable on the drum in a figure of eight configuration and blow towards blowing pit E and coil of 10 - 15m of OFC should be kept in pit E. v) Since the cable will be available in length of 3 km and above, so the contractor has to plan the location of blowing pits before laying of HDPE duct. The contractor has to ensure that excess OFC is not coiled in the blowing pit and also optical fibre cable does not fall short of the location of blowing pit. The contractor has to match the cable drum length with the location of blowing pits, to ensure minimum cut length and wastage of OFC. To achieve the blowing of above shown strength, blowing can be carried out downhill, wherever possible. vi) HDPE ducts will be sealed with the help of cable sealing plugs after blowing of OFC into the duct at jointing pit locations. 13.8.11 TREATMENT OF CABLE AFTER IT IS LAID a. After completion of cable laying check the following items: ⮚ Confirm extra jointing length as required at end. ⮚ In case cable is damaged, take necessary prevention and remedial steps for removal of defects. ⮚ If there is any snaking or rise in cable put right. ⮚ Examine the interior of the trench and remove any pebbles, etc. ⮚ Take protective steps for such objects projecting the trench such as sewer pipe etc. b. While laying one piece of cable, when part of the work is to be put off till the following day, keep the remaining portion of cable wound on the drum, reduce as much as possible the distance of the drum from already laid cable considering cable bending radius and general traffic safety and also ensure that drum is prevented from tumbling down or rolling away. Already laid cable shall be fully covered to avoid outside interference. ******** Indian Railways Telecom Manual - 2021 Page 138 SECTION – IX PROTECTION OF OPTIC FIBRE CABLE ROUTE AND BACK FILLING OF TRENCHES 13.9.1 GENERAL : 13.9.2 This chapter covers the various protection arrangements, which are required to be provided along the cable route for the purpose of preventing damage to the cable and protection to staff. 13.9.3 The chapter also covers the arrangement for back filling of cable trenches to provide protection to the cable. 13.9.4 PROTECTION OF CABLE ROUTE : 13.9.5 PROTECTION OF CABLE CROSSING BRIDGES/CULVERTS. The typical arrangements for protection for the following types of bridges/ culverts are as under. i) Arrangement of cable troughs and channel for girder bridges and major culverts (Typical Drawing RDSO/TCDO/COP-12) and RDSO/TCDO/ COP-13). Separate troughs should be provided for laying 6 quad cable & OFC. For smaller culverts/bridges, if feasible, trenchless horizontal directional drilling (HDD) should be adopted with DWC pipe protection and ensuring that cable is minimum 2 m below the bed of culverts/ bridges. ii) Drawing of crossing major culverts (high flood level and normally blocked by water) and major bridges by steel troughs at rail level (Typical drawing RDSO/TCDO/COP-14(a)). iii) Drawing of crossing of Railway bridges by perforated GI pipe (Typical drawing RDSO/TCDO/COP-17(a)). iv) Drawing for crossing culverts pipe/box with high flood level (Typical Drawing RDSO/TCDO/COP-16(a)). 13.9.6 MEASURE AGAINST THEFT OF STEEL TROUGHS : (a) In the drawing for major culverts and bridges steel troughs are to be provided on the channels as indicated in the drawing RDSO/TCDO/COP-12 and RDSO/TCDO/COP-13. (b) In order to prevent theft of optic fibre cable steel troughs with optic fibre cable should be filled up by bitumen compound conforming to IS specification. The cover of the trough to be effectively secured as per the drawing. (c) Bitumen filling job should be supervised at a responsible level not below the rank of Sr. Supervisor. (d) In order that the temperature of the cable does not increase beyond 55°C, bitumen compound should be poured in the early hours/late hours of day when ambient temperature is around 18°C or less. Indian Railways Telecom Manual - 2021 Page 139 (e) While pouring the heated bitumen compound, steel trough covers should be removed all through the bridges in order to permit fast cooling. (f) Before pouring bitumen compound, its temperature should be accurately measured to ensure that the pouring temperature is not more than 140°C. (g) The bitumen compound should be filled upto a height of approximate 60mm. (h) Both End of steel troughs should be concreted at the end of bridge/culvert 13.9.7 ARRANGEMENT ACROSS CULVERTS : (a) Most of the culverts are generally dry and as such the arrangement as indicated in RDSO/TCDO/COP-17(a) can be adopted. (b) For culverts which are normally filled with water or which are having high flood level, the protection arrangement can be done as per the arrangement shown in drawing RDSO/PCDO/COP-16(a). 13.9.8 ARRANGEMENT FOR LAYING OF FIBRE OPTIC CABLE ACROSS GIRDER BRIDGES : (a) Girder bridges up to span length of 12 meter : i) Girder bridges of up to 6 meter span can be crossed with perforated GI pipe as per the arrangement shown in drawing No. RDSO/TCDO/COP-17(a). ii) The same arrangement can be followed for girder bridges of span length between 6 and 12 meter where an intermediate support to GI pipe can be provided. (b) Girder bridges of span length more than 12 meters. i) The crossing of girder bridges of more than12 length can be done as per the drawing No. RDSO/TCDO/COP-14(a). The arrangement for fixing of steel trough indicated in drawing RDSO/TCDO/COP-12 and RDSO/TCDO/COP-13. ii) The procedure for filling bitumen compound is indicated in Clause 13.9.6 above. iii) Separate trough for laying 6 quad cable should be used. 13.9.9 PROTECTION ARRANGEMENT ON THE CABLE ROUTE : The typical drawings of cable trenches under various situations are given in Section-VIII. These drawings include the protection arrangement of brick provided along the cable route. These protection arrangements are summarized below: (a) The cable laid in the station yard (Home Signal to Home signal) and on the embankment, after covering the duct with riddled earth, B-class Indian Railways Telecom Manual - 2021 Page 140 brick to be placed transversely through out to over the cable laid in station yard/embankment. (b) The cable marker shall normally be provided at distance of every 50 meters on the cable route and at places wherever the route changes. A joint indicator shall be provided at all joints. The cable marker and joint marker provision shall be as per Drawing No. RDSO/TCDO/COP- 22(a) for normal and rocky area. (c) The cable marker and joint markers provided shall be of standard stone RCC type. 13.9.10 CABLE CROSSING TRACKS AND LEVEL CROSSING GATE : To the extent possible, track crossings within the station yard requiring crossing of number of tracks to be avoided. Wherever it crosses the track or LC gate: (a) The cable shall be laid in RCC/DWC ducts keeping the depth same as in normal routes. (b) In case of cable crossing the LC gates, RCC/DWC ducts to be laid on the road and for a distance of at least two meters from either side of the road. (c) Minimum depth at any track crossing shall not be less than 1.2 meters with RCC/DWC duct. In case cable crossing the track, it may be ensured that it should not be bent less than 600mm radius. Suitable fixture with RCC/DWC duct should be provided to ensure proper bending radius to be used at each end. (d) The drawing for track crossing, road crossing platform shall be as per Drawing No. RDSO/TCDO/COP-19(a). (e) Arrangement of RCC/DWC duct under metalled road shall be as per RDSO/TCDO/COP-20(a) (f) In case of Road/Platforms/Railway track etc. trenchless horizontal directional drilling should be adopted. A minimum depth of 1.2 meters to be ensured. (g) Cable should be taken in GI pipe in rocky areas, culverts, girder bridges and PSC girder bridges (without duct). At the end of these structures where the pipe enters the trench the pipe should extend right into the trench and then should be protected with a concrete/brick masonry work, 5 meter cable should be kept at the ends. (h) Wherever new PSC girders are being constructed, provision of ducts should be catered, OFC cable shall be taken through class B GI pipes of 80 mm diameter. (i) Inside the tunnels, the cable should be laid by excavating a suitable depth in the drainage area levelling the bottom surface in B class GI pipe of 80 mm diameter, the entire length of GI pipe will be concreted and substantially protected. Another method may be clamping of DWC ducts to side walls of tunnels at safe height. (j) Wherever new track is constructed inside tunnels, provision for DWC duct should be catered which can be embedded in the concrete base to be ensured by Engineering unit constructing tunnels. Indian Railways Telecom Manual - 2021 Page 141 (k) The joints should be avoided inside tunnels. If the tunnel length is more than 3 kms suitable area with proper finishing inside tunnel refuge to be earmarked for housing OFC joints and telecom equipment. 13.9.11 BACK FILLING OF TRENCHES: For back filling of cable trenches following precautions shall be taken: (a) At least 120 mm from the surface of the last cable, cable should be covered with riddled earth. This portion of the earth is not loose. This will also prevent entry of rodents and other insects. (b) At 500 mm depth a PVC warning tape shall be provided continuously running in the trench. (c) For the remaining portion of the trench, the released earth may be used. However, after filling up the trench, the earth shall be consolidated by ramming. (d) Back filling of trench and ramming shall be supervised by a responsible Supervisor and also at officer’s level for the specified percentage of the section. In case of shortage of manpower, video recording of cable laying, depth of trench, protection arrangement and back filling of trenches should be included in scope of contract. All these recordings should be handed over to concerned SSE/Tele/Maintenance along with handing over of section. (e) It shall be ensured that before the start of monsoon session, all open trenches are properly back filled to avoid water logging of the trench. *********** Indian Railways Telecom Manual - 2021 Page 142 SECTION – X JOINTING AND TERMINATION OF OPTIC FIBRE CABLE 13.10.1 Techniques for jointing of optic fibre cable. 13.10.2 Following types of techniques shall be used for splicing of fibres :- (a) Mechanical Splice This aligns the axis of the two fibres to be joined and physically hold them together. (b) Fusion Splicing This is done by applying localized heating (i.e. by electric arc or flame) at the interface between the butted, pre-aligned fibre end, causing them to soften and fuse together. 13.10.3 Mechanical splicing may be used only for temporary splicing of fibres. 13.10.4 At all other locations and during initial installation of optic fibre cable, fusion splicing shall be adopted. 13.10.5 STRAIGHT JOINT FOR OPTIC FIBRE CABLE There are various types of joint enclosures available in the market. The procedure for assembly of joint closure is described in the installation manual supplied with straight joint closure. This includes the following : (a) Material inside joint closure kit. (b) Installation tools required. (c) Detailed procedure for cable jointing (d) Procedure for reopening the closure. 13.10.6 Generally, the following steps are involved for jointing of the cable : - Preparation of cable for jointing - Stripping/cutting the cable - Preparation of cable and joint closure for splicing - Stripping and cleaving of fibres - Organising fibres and finishing joints - Sealing of joint closure and - Placing joint in pit Indian Railways Telecom Manual - 2021 Page 143 13.10.7 PREPARATION OF CABLE FOR JOINTING (a) During the installation, a minimum of 10 meter of cable at each end is coiled in the jointing pit to provide for jointing to be carried out at convenient location as well as spare length to be available for future use in case of failures. (b) The pit size shall be so as to ensure the length of the wall on which joint is mounted is greater than closure length plus twice the minimum bending radius of the cable. A pit length of 1 meter is sufficient for most of the cable and joint closures. Bracket to support the cable coil are also fixed on the wall of the pit. Details of cable pit are given in Drawing No.RDSO/TCDO/COP-21(a). (c) The cable is then coiled on to the pit wall in the same position as required after the joint is complete. The marking is done on all the loops so that it will be easier to install it later. 13.10.8 STRIPPING/CUTTING OF THE CABLE (a) The cable is stripped of outer and inner sheath with each sheath staggered approximately 10mm from the one above it. (b) Proper care must be taken when removing the inner sheath to ensure that the fibres are not scratched or cut with the stripping knife or tool. To prevent this, it is better to score the inner sheath twice on opposite sides of the cable, rather than cutting completely through it. The two scores marking on either side of the cable can be easily stripped of the inner sheath by hand. (c) The fibres shall be then removed from cable one by one and each fibre is cleaned individually using kerosene/suitable liquid to remove the jelly. (d) Armouring shall remain outside the gland and will not be connected through. 13.10.9 PREPARATION OF CABLE JOINT CLOSURE FOR SPLICING The type of preparation work performed on the cable prior to splicing differs on the type of joint closure and fibre organizer used. However, the following steps shall be usually common for different types of joint closure. (a) The strength member of each cable shall be joined to each other and/or the central frame of the joint closure. (b) The joint closure shall be assembled around the cable. (c) The sealing compound or heat shrink sleeve shall be applied to the cables and closure, or prepared for application after splicing is complete. Indian Railways Telecom Manual - 2021 Page 144 (d) Tags which identify the fibres number shall be attached at suitable location on the fibres. (e) Splice protectors shall be slipped over each fibre in readiness for placing over the bare fibre after splicing. 13.10.10 STRIPPING AND CLEAVING OF FIBRE (a) Prior to splicing, primary protective coating of each fibre shall be stripped off up to length of 50 mm. by using fibre stripper. Fibre strippers shall be manufactured to fine tolerances and only score the coating without contacting the glass fibre. (b) The bare fibre shall be then wiped with a lint tissue paper rinsed with ethyl alcohol. (c) Cleaving of the fibre shall then be performed to obtain as close as possible to a perfect 90 degree face on the fibre. 13.10.11 SPLICING OF THE FIBRE 13.10.12.1 FUSION SPLICING OF FIBRE Some of the general steps with full automatic microprocessor control splicing machines shall be as under: i. Hands shall be thoroughly washed prior to commencing this procedure. ii. The clean bare fibre shall be dipped in the beaker of ethyl alcohol of the ultrasonic cleaver and ultrasonic clever switched on for 5-10 seconds. iii. The bare fibre shall then be placed inside ‘V’ groove of the splicing machine by opening clamp handle, in such a way so that 1 mm gap is available between the electrodes and the end of fibre being spliced and heat shrink protector inserted. iv. The same procedure shall be repeated for other fibre. v. The start button on the splice controller shall be pressed. vi. The machine shall pre-fuse set align both in ‘X’ and ‘Y’ directions and then finally fuse the fibre. vii. The splice shall be inspected on monitor provided on the fusion splicing machine, there shall be no nicking, bulging and cores are adequately aligned. The above procedure shall be repeated if the splice is not visually good looking. viii. The heat shrink protector shall be slid over the splice and tube shall be placed in tube heater. Heating shall be considered complete when soft inner layer is seen to be ‘oozing’ out of the outer layer of the protector. ix. The steps 9a) to (h) above shall be repeated for other fibres. 13.10.12.2 MECHANICAL SPLICING OF THE FIBRE There are two types of mechanical splicing system. In case, one with precision alignment of fibre in ‘V’ groove and fibre ends are sealed with some index matching fluid and adhesive. The other system uses Indian Railways Telecom Manual - 2021 Page 145 ultrasonic light source for curing optical adhesive in addition to alignment etc. The general steps involved above are as under: (a) Stripping and cleaving of fibres shall be done as per Clause 13.10.10. (b) Protective end cap shall be removed from mechanical splice and vent tube pulled up. (c) Adhesive shall be injected into splice as specified by supplier into splice. (d) Fibre shall be inserted till it butts against fibre end already bonded in place. (e) Adhesive shall be cured with UV light following exposure times as specified by the supplier. (f) The steps (a) to (e) above shall be repeated for all fibres. 13.10.12 ORGANISING FIBRE AND FINISHING JOINTS (a) After each fibre has been spliced, the heat shrink protection sleeve shall be slipped over the bare fibre before any handling of fibre takes place as uncoated fibres are very brittle and cannot withstand small radius bends without breaking (b) The fibre shall then be organized into its tray by coiling the fibres on east side of the protection sleeve using the full tray side to ensure the maximum radius possible for fibre coils. (c) The tray then shall be placed in the position (d) OTDR reading shall be taken for all splices in this organized state and recorded on the test sheet to confirm that all fibres attenuation is within specified limits. The OTDR test confirms that fibres were not subjected to excessive stress during the organizing process. Care should be taken that the fibres are not interchanged while jointing. (e) The joint shall then be closed with necessary sealing etc. and considered ready for placement in the pit. 13.10.13 PLACING OF COMPLETED JOINT IN PIT (a) Joint shall be taken out from the vehicle and placed on the tarpaulin provided near the pit. (b) The cable is laid on the ground and looped according to the marking done in the beginning. These loops shall then be tied together with the tape. (c) The joint shall be permanently closed and sealed by heating heat shrinkable sleeve, etc. (d) The joint closure shall be fixed to the bracket on the pit wall and pit closed. 13.10.14 REOPENING OF THE JOINT Indian Railways Telecom Manual - 2021 Page 146 For attending faults, etc. special kits shall be used for opening of the joint and the instructions shall be followed. The general steps are as under:- (a) Suitable knife shall be used to cut heat shrink sleeve longitudinally along its entire length. (b) It shall be ensured that there is no damage to the smaller heat shrink sleeve on the ends of the joint. (c) Heat shall then be applied to the cut sleeve until it begins to separate. (d) The cut sleeve shall be removed gently from the joint so that joint can be opened. (e) Protective sleeve/cover shall be removed for attending to faults, etc. 13.10.15 TERMINATION JOINT FOR OPTIC FIBRE CABLE This joint is provided in the cable hut for terminating the outdoor optic fibre cable of both the sides, splicing through fibres, connecting fibres to pigtails for connection to optical line terminal equipment, etc. The procedure for installation of termination joint box shall depend on the type of joint enclosure. The installation manual shall contain the step by step procedure for installation. The general steps shall be as under: - Marking the cable - Stripping/cutting the cable - Gripping cable in sheath/clamp - Treatment of tension member - Fibre splicing - Enclosing fibre - Fixing strength member - Closing the cover - Fixing termination box - Fixing the cable 13.10.16 MARKING THE CABLE (a) The cable length shall be determined up to the proposed location of termination box. It shall also be ensured that at least 10 meters of cable is coiled in the cable pit. (b) The cutting point shall be determined and the cable marked. (c) The length sheath peeling point shall be determined and cable marked. 13.10.17 CUTTING/STRIPPING THE CABLE (a) The cable shall be cut as per the marking. (b) The sheath shall be removed from cable end. During sheath stripping care shall be taken that the fibres are not damaged. (c) The length and the steps for various sheath cutting shall be as per the instructions given in the manual. Indian Railways Telecom Manual - 2021 Page 147 13.10.18 GRIPPING THE CABLE (a) PVC tape shall be wound around the cable core just beside edge of the sheath. (b) The bushing inside sheath shall be inserted by cutting the cable sheath for about 25mm. (c) The sheath grip (lower half and upper half) shall be placed and tightened it with the help of torque wrench. 13.10.19 FIXING OF TENSION MEMBER (a) The tension member shall be marked for the specified length and cut. (b) The tension member shall be thoroughly cleaned by alcohol and cotton cloth. (c) Tension member holder shall be fixed at the end of tension member with the help of instant adhesive. 13.10.20 FIBRE SPLICING The procedure for fibre splicing shall be same as described for straight joint closure in Clause 13.10.12. 13.10.21 ENCLOSING FIBRES (a) The fibre cassette shall be set on the base of the joint closure. (b) Excess length of fibre shall be arranged to make double figure of eight. (c) The spliced fibre and its excess length shall be enclosed carefully. (d) The steps (a) to (c) above shall be repeated for other fibres. 13.10.22 MOUNTING OF TERMINATION BOX/FDMS Termination box/FDMS is fixed either on wall or on equipment rack. (a) The fixing holes are marked on the walls/bracket/frame. (b) The termination box is placed and the nuts inside the base box shall be tightened. (c) Sufficient silica gel in bags are kept inside and the covers shall then be put on termination box and closed. (d) Fibre Distribution Management System (FDMS). In all future installations, OF cable should be installed in the suitable Fibre Distribution and Management System (FDMS). The FDMS shall conform to latest TEC/RDSO specification. (e) Patch Cords/Pigtails. Patch cords and pigtails shall be procured as per RDSO/TEC’s latest specification. (f) Jointing/Splicing: The optic fibre placed in the joint should be safely protected in a RCC concrete chamber as per RDSO drawings. The chamber should be filled with fine sieved sand. The upper surface of the chamber should be kept 50 cm below the surface; a suitable joint Indian Railways Telecom Manual - 2021 Page 148 marker should be placed on all joint locations. 10 m of extra cable should be coiled in the pit for future use. Armouring must not be put through. The armouring of OFC should be earthed at all locations with new/existing available telecom/signalling earthing arrangements. In absence of earthing, it must be properly wrapped with insulator tape in order to prevent electric shock to the working staff. 13.10.23 FIXING THE CABLE The cable on the wall/frame shall be secured at two places within 1 m from the termination box keeping in view the straight entry of cable into termination box. After the cable is laid and splicing has been completed, measurements in the enclosed proforma has to be prepared. Section Distance Cable Fibre Loss in dB Remarks length No From To 1310nm 1550nm The end to end loss should not exceed 0.25db/Km at 1550 nm and 0.40 db/Km at 1310 nm. ******** Indian Railways Telecom Manual - 2021 Page 149 SECTION – XI TOOLS AND EQUIPMENTS FOR INSTALLATION AND TESTING OF OPTIC FIBRE CABLE GROUP – I TOOLS REQUIRED FOR TRENCHING, CABLE LAYING AND BACK FILLING. SNo. Tool’s Name 1. Cable Jack 2. Cable Grip 3. Reopening device 4. Free Hood Hook 5. Shackle free head hook 6. Growling hook 7. Pulling bolt 8. Tension meter 9. Pulley 10. Anti twist device (swivel) 11. Roller 12. Flexible cable 13. Pulling rope 14. Brush 15. Mandrel 16. Chain 17. Measuring cord for strain gauge 18. Slip winch 19. Wire rope 20. Portable VHF set 21. Measuring tape 22. Phawarah 23. Iron Plate 24. Loader Backhoe for drilling 25. Warning Tape 26. Caterpillar tractor 27. Fork lifter 28. Tool Van vehicle 29. Tachometer 30. Portable Generator 31. tent type Umbrella 32. Blank dark coloured cloth for splicing machine Indian Railways Telecom Manual - 2021 Page 150 GROUP – II TOOLS AND EQUIPMENTS REQUIRED FOR JOINTING AND TERMINATION OF OPTIC FIBRE CABLE. SNo. Tool’s Name 1. Branch Joint Closure 2. Termination Box 3. Rubber and Block 4. Sheath Clamp 5. Bushing 6. Strength Member holder 7. Heat Shrinkage tube 8. Arc fusion splicer machine 9. Power cord AC/DC 10. Walkie-Talkie with spare battery 11. Tube heater 12. Precision cleaver 13. Cable sheath stripper 14. Fibre stripper 15. Knife for HDPE cutting 16. Hacksaw for strength membrane 17. Isopropyl alcohol or methanol of high specific gravity 18. Johnson Buds 19. Tweezers 20. Gun heater blower type 21. Sleeve for splice protection 22. OTDR 23. Stabilized optical power source and power meter 24. Stickers for numbering of splicers ******** Indian Railways Telecom Manual - 2021 Page 151 SECTION – XII 13.12.1 List of items to be handed over to the Maintenance Organization before handing over the section for maintenance. The following items should be handed over to the maintenance in charge before handing over the section for maintenance. 1. The Cable Route Plan in electronic form (CD) preferably using AUTOCAD. Distances from fixed reference structures like centre of track, OHE mast, bridges, culverts, etc. should be indicated in the route plan for easy reference in future. 2. The Fibre Distribution Plan 3. Measurements of Optical Parameters which includes sectional losses, splice wise losses, set of measuring equipment, programing/maintenance terminal and tools & plants should be handed over to the maintenance organization. 4. Joint test report of important parameters for all fibres Jointly done by Construction/Railtel with Maintenance organisation. 5. OEM Manuals, warranty certificates of all Telecom equipment with pre commissioning check list if any. 6. Spare materials 13.12.2 Staff Requirement. OFC in each section should be maintained by a cable gang. The staff strength should be as per the latest yardstick issued by Railway Board. The maintenance gang should have provision for a vehicle where the men and material can be loaded and comfortably reach the site. ******** Indian Railways Telecom Manual - 2021 Page 152 APPENDIX – I MAINTENANCE SCHEDULE FOR FIBRE OPTIC SYSTEM EQUIPMENT ITEM TELECOM SECTIONAL SUPERVISOR TECHNICIAN SUPERVISOR INCHARGE POWER Maintenance of monthly Quarterly Half yearly SUPPLY Batteries EQUIPMENT Meas. of Battery fortnightly monthly Quarterly voltages Meas, of Charger fortnightly monthly Quarterly In/Out voltages and currents Checking of fuses fortnightly monthly Quarterly and terminations Checking of fortnightly monthly Quarterly Earthing connections GENERAL Removal of dust weekly from the equipment and cards. Ensuring cleaning of the flooring Measurement of weekly room temperature Measurement of Quarterly Yearly earth resistance Check of electrical weekly monthly Yearly services ( lights, fans, ACs etc.). Maintenance of Quarterly Yearly pigtails, fibre distribution frame etc. OPTICAL OTDR Quarterly Yearly FIBRE Measurement of CABLE spare fibres CABLE Integrity of cable monthly ROUTE route Protective works monthly Quarterly Yearly on bridges & culverts Cable route monthly Quarterly Yearly markers Earthing of sheath monthly Quarterly Yearly of cable Periodical OTDR Yearly line up measurement on Indian Railways Telecom Manual - 2021 Page 153 all Fibres, Tx/Rx optical power loss, Error performance measurement Note : 1. Items related to cable gang shall be done by cable maintenance Gang. 2. Items related to equipment shall be done by the equipment maintenance gang. Indian Railways Telecom Manual - 2021 Page 154 APPENDIX - II T&P ITEMS AND MEASURING EQUIPMENTS FOR MAINTENANCE STAFF S.No. GANG RECOMMENDED T&P ITEMS & EQUIPMENTS 1. Equipment Soldering Iron Maintenance Vacuum Cleaner Standard Tool Kit containing Screw Drivers, etc. Digital Multi-meter Optical Fibre connector Cleaning kit 2. Sectional Supervisor All equipments as prescribed for Equipment equipment maintenance gang. Portable BER & PCM Test Set (For STM) Meager Optical Attenuation Measurement set consisting of optical power meter, optical source and optical attenuator 3. Supervisory Incharge Test and Repair Van for equipments PCM Transmission Analyzer (For STM) PCM Channel Analyzer along (For STM) Fibre Optic tool kit Mini portable Generator 4. Sectional Engineer Digital Multi-meter Cable Maintenance Mini ODTR Mechanical splicing kit Optical Fibre cable 200 Mts Splicing machine with battery Fibre Optic Tool Kit All types of Adopters & Connectors Insulation Tester TMS kit 5. HQ gang for cable Test & Repair van Portable generator Automatic Fusion Splicing machine OTDR Fibre Optic Tool Kit Cable route tracer Mechanical Splicing kit All types of Adopters & Connectors. Lighting arrangements and emergency lamps (2 Nos) PCP sets (4 Nos) Walkie-Talkie sets (4 Nos) Torches with batteries (6 sets) Indian Railways Telecom Manual - 2021 Page 155 Spare batteries for splicing machines (1 No) Puncha (to remove ballast) (2 Nos) Pickaxe (4 Nos) Motar pan & showel (4 Nos) Spade (4 Nos) Portable tent (1 No) Crow bar (2 Nos) OFC spare cables (cables of adequate length) HDPE pipe pieces (10 Nos) Drinking water can (20 litres) (1 No) Glasses (2 Nos) Folding table and chair (1 each) Stool light weight (2 Nos) First aid box (1 No) Indian Railways Telecom Manual - 2021 Page 156 Indian Railways Telecom Manual - 2021 Page 157 Indian Railways Telecom Manual - 2021 Page 158 Indian Railways Telecom Manual - 2021 Page 159 Indian Railways Telecom Manual - 2021 Page 160 Indian Railways Telecom Manual - 2021 Page 161 Indian Railways Telecom Manual - 2021 Page 162 Indian Railways Telecom Manual - 2021 Page 163 Indian Railways Telecom Manual - 2021 Page 164 Indian Railways Telecom Manual - 2021 Page 165 Indian Railways Telecom Manual - 2021 Page 166 Indian Railways Telecom Manual - 2021 Page 167 Indian Railways Telecom Manual - 2021 Page 168 Indian Railways Telecom Manual - 2021 Page 169 Indian Railways Telecom Manual - 2021 Page 170 Indian Railways Telecom Manual - 2021 Page 171 Indian Railways Telecom Manual - 2021 Page 172 Indian Railways Telecom Manual - 2021 Page 173 Indian Railways Telecom Manual - 2021 Page 174 Indian Railways Telecom Manual - 2021 Page 175 Indian Railways Telecom Manual - 2021 Page 176 Annexure-I DUCT INTEGRITY TEST (DIT) 1.1 Duct Integrity Test (DIT) is to be carried before OFC cable blowing. The Purpose of duct integrity Test is to ascertain and ensure the suitability of the duct for cable installation through jetting. It is first necessary to ensure that the duct into which cable is to be installed is continuous over the length of the duct. Some reasons for lack of continuity are: Missing Sections of Duct. Couplers not connected. Over lapping of Ducts. 1.2 The Air Test establishes the duct continuity. Air is introduced from one end of the duct. If air comes out from the other end of the duct, then it is established that the duct is continuous. If no air emerges, then the fault is to be identified and corrected before proceeding further. Duct overlap can lead to potentially very dangerous situation and should be corrected promptly. 1.3 Second step in the DIT Test is to establish that there is a clear passage for the cable to go through the duct. Possible reasons for lack of clear passageway are: Kink in the Duct. Blockage in the Duct. 1.4 These deficiencies are to be corrected before proceeding further. Kink in the duct may be caused at the duct laying stage when back filling may have been done without taking care to keep boulders out of the way and out of the trench. A fallen boulder on top of a laid duct can cause the problem. The kink may also have been caused at the de-coiling stage, when this is attempted without use of a de-coiler. 1.5 The kink in the buried duct is located through the shuttle Test. A suitable shuttle is first passed through the duct. The shuttle will get stuck at the point where the duct is either kinked or blocked. Next a transmitter is passed through the duct. It gets stuck behind the shuttle. The path of the duct is then tracked with a receiver. As the receiver passes over the transmitter, the signal from the transmitter is heard loud and clear. In this way the transmitter, and just a head the shuttle, and just ahead the kink are located. The spot is marked and the trench has to be dug up again. The boulder responsible for the kink is removed. The portion of the damaged pipe is cut and replaced with good duct of equal length. Joint with laid duct is made with push-fit coupler. 1.6 Cable installation through jetting can be carried out successfully only under a pressure of 10 bar. Before cable installation is attempted it is necessary to verify that the duct can hold this pressure. This is the major purpose of the pressure Test. 1.7 Possible reasons for failure of DIT pressure test are: Indian Railways Telecom Manual - 2021 Page 177 Leakage at Couplers. Puncture in Duct. 1.8 Coupler leakage is caused by improper installation of coupler. A puncture in the duct can result from improper handling of the duct. A sharp-edged boulder if it should come to rest on top of the buried duct can also puncture the duct. Air leakage from the leaking coupler or the punctured duct is the tale sign of the problem which can then be rectified. 1.9 Thus, in summary, the DIT Test is conducted prior to cable blowing/pulling with a view to check and if necessary rectify so it is made suitable for cable blowing/pulling. The possible duct faults that may show up during the DIT Test process are: Missing sections of duct. Couplers not connected. Overlapping of Ducts. Kink in the Duct. Blockage in the Duct. Leaking at Couplers. Puncture in Duct. 1.10 These faults are to be corrected before proceeding further. The DIT Test consists of the following 4 important steps: 1) Air blowing purpose is to ensure that there are no discontinuities (or missing sections) in the duct. 2) Shuttle of a diameter 80% of the duct inside diameter and of 150 mm length is passed through the duct. Purpose is to check for bends, kinks, crush and deformity in the duct. 3) Sponge of a diameter two times the duct inside diameter, and length of 100 mm is blown through the duct. Purpose of passing, the sponge through the duct is to clean the duct. 4) Pressure test is conducted at 5 bar pressure for 30 Minutes with maximum permissible drop of 0.5 bar. 1.11 Air blowing: Air is introduced into the duct and a check is made at the end of the 2 Km section of duct. Possibilities are: Normal flow of air is perceived at the other end. So far, so good, proceed further with the DIT Test. No flow of air at the other end of the duct. Trouble is indicated, Leakage at couplers, puncture in duct, missing duct, duct overlap, blockage in the duct. Less than normal flow of air. Leakage at couplers, puncture in duct. If there is no flow of air at the other end, check the pressure at the point where air is introduced into the duct. If the pressure is less than normal this would rule out blockage in the duct. It would indicate leakage from the duct or at a Indian Railways Telecom Manual - 2021 Page 178 coupler location. Higher than normal pressure, would indicate blockage in the duct. The problem can be localized by opening the coupler at the 1 Km point and introducing air once again through the duct. This will help identify whether the problem exists in the first kilometer of the duct under check or in the second kilometer. 1.12 Shuttle Test: Once the air test has been successfully concluded, a shuttle of a diameter 80% of duct inside diameter and of 150 mm length is passed through the duct. Purpose is to check for bends, kinks, crush and deformity in the duct. If the shuttle passes through successfully this confirms that the bends in the duct are gradual and there are no kinks or deformity that would hinder the progress of the cable during the installation process. The shuttle should pass through the 2 Km of duct length in a space of three minutes. In case there is a problem and the shuttle does not emerge from the other end of the duct even after 5 to 6 minutes, then a transmitter is to be blown through the duct to identify where the shuttle is stuck. A receiver at the 1 km point will pick up the signal from the transmitter as it goes by, and in this way it will be known that the shuttle is stuck in the second kilometer of duct. If no signal is picked up then the problem would have been localized as existing in the first kilometer, shuttle, and the kink in the duct would be identified, and the duct can be suitably rectified. Often times the shuttle gets stuck due to a minor kink, and when the transmitter is blown the shuttle and transmitter both come out the same time. 1.13 Sponge Blowing: Purpose of blowing sponge through the duct is to clean it. A sponge of a diameter twice the inside diameter of the duct, and 100 mm in length, is blown through the duct. The time required for the sponge to pass through the 2 Km duct length is three minutes. 1.14 Pressure Test: The pressure test is conducted at 5 bar pressure. Over a 30 minutes period the pressure loss should not exceed 0.5 bar. Once this pressure test passed, the duct is pronounced ready and fit for cable blowing/pulling. -x-x-x- Indian Railways Telecom Manual - 2021 Page 179
