Cabling Planning & Route Selection

Cabling Planning & Route Selection

• Determine the number of conductors, cable size and type needed (quad/PIJF) based on desired circuit type.
• Zonal Railway may allocate quad on the 6Q including BPAC/IBS.
• A 25% or more conductor spare is recommended for cables with 5 or more pairs, due to long cable lifespan and future expansion needs.
• Choose the best cable route by walking/travelling along the track and identifying the optimal alignment.
• Clearly depict the chosen route on a route plan, showing track alignment, offsets from permanent structures, and crossings (road, track, power cables, water and sewage mains).
• Existing power cable routes and other relevant information should be included on the route plan.
• Identify convenient distribution points for connecting main cables to smaller distribution cables (e.g., subscriber cabling for exchange, emergency socket locations).
• Telecommunication cables should generally be laid within 1 meter inside the Railway boundary (refer to boundary pillars or, if absent, contact P.Way/works officials).
• Maintain a minimum distance of 2 meters from the nearest track and beyond embankment.
• Trench work within the formation area of the track should be done only after consultation with P.Way staff and filled/rammed properly before sunset on the same day.
• Ensure separation of at least 1 meter between telecommunication cable and nearest electrical power cable.

Cable Marker Placement & Depth

• Provide cable markers at 50 meter intervals along the route.
• Additional markers should highlight important points like cable joints, water and sewage mains, power cable crossings, alignment bends/curves.
• Use Quad cable RCC route marker (Drawing no.RDSO/TCDO/COP-22(a) in chapter XIII, painted red).
• Paint Quad cable joint markers yellow on all sides for easy identification.
• Bury the cable at least 1 meter below ground level.
• Ensure sufficient trench width for easy cleaning and cable laying.

Special Considerations Near OHE & Other Structures

• In yards or where trench depth is limited to 0.5 meters, maintain a minimum of 1 meter distance between cable and OHE mast supporting the catenary or other structures likely to come in contact with high tension conductors.
• If the 1 meter distance cannot be maintained, lay the cable in concrete pipes to reduce the required distance to 0.5 meters.
• When trench depth exceeds 0.5 meters near OHE masts, ensure the nearest edge of the trench is at least 3 meters away from the mast.
• Mark cable joint positions on the nearest OHE mast with an approved legend.

Cable Laying in Vicinity of Substations & OHE Switching Stations

• In vicinity of traction substations, lay cable at least 1 meter away from any metallic body fixed in the ground and 1 meter away from substation earthing.
• Lay cables in concrete pipes/enclosed brick channels for 300 meters on both sides of the substation.
• Preferably lay cable on the track side opposite the substation.
• Near OHE switching stations, lay the cable at least 1 meter away from any metallic body fixed in the ground and 5 meters away from station earthing.
• Reduce the 5 meter distance from station earthing to 1 meter if the cables are laid in concrete piles.
• Lay cables at least 1 meter away from independent earthing provided for OHE structures.

General Cable Spacing & Laying Practices

• Outside station limits, lay cables at a standard distance of 10 meters from the center of the nearest track.
• When laying signalling and telecommunication cables in the same trench, maintain a 100 mm distance using bricks at 2-meter intervals.
• Do not lay HT, LT power cables and telecommunication cables in the same trench.
• Bury cables parallel to the track 1 meter below the ground, and those laid across the track 1 meter below rail flanges.
• Keep the telecommunication cable trench as far away as possible from the power cable trench.
• Follow approved methods for laying cables along girder bridges, over culverts, through culvert beds, over rocky terrain, etc.
• Avoid sharp bends in cables during laying.
• Ensure bending radius for aluminium sheathed armoured cables is at least 40 times the cable diameter.
• Generally lay OFC and quad cables in the same trenches (refer to chapter XIII for drawings).

Cable Planning and Laying

• Cable Type and Quantity: Determine the number of conductors, sizes, and cable type (quad/PIJF) based on circuit requirements. Zonal Railways may allocate quad on the 6Q for BPAC/IBS.
• Future Expansion: Reserve at least 25% of conductors for future expansion in cables with 5 or more pairs, considering their long lifespan.
• Route Planning:
  • Route Selection: Walk or travel along the track to identify the best alignment for the cable route.
  • Route Diagram: Create a route plan showing the alignment, offsets from permanent structures, crossings (road, track, power cable, water and sewage mains), and other important points.
• Distribution Points: Choose convenient locations for cable distribution (main cable to smaller cables for subscribers, emergency sockets, etc.).
• Cable Layout:
  • Railroad Boundary: Lay telecom cables within 1 meter of the railway boundary.
  • Distance from Track: Maintain at least 2 meters from the nearest track and beyond the embankment.
  • Trenches:
    • Consult with P.Way staff before digging trenches in or near the track formation area.
    • Fill and compact trenches immediately after laying cables, especially during monsoon season and in alluvial soil.
    • Ensure at least 1 meter separation from electrical power cables.
• Cable Markers:
  • Use cable markers at 50-meter intervals.
  • Include markers for cable joints, water and sewage mains, power cable crossings, alignment bends/curves, etc.
  • Use RDSO/TCDO/COP-22(a) markers painted red, with yellow enamel for quad cable joints.
• Cable Depth:
  • General depth: Lay cables at least 1 meter below the surface.
  • Limited Depth: Maintain at least 1 meter between the cable and overhead equipment (OHE) masts when depth is limited to 0.5 meters.
  • Deep Trenches: Maintain at least 3 meters between the OHE mast and the nearest edge of the cable trench when depth exceeds 0.5 meters.
• Cable Joints: Mark cable joint positions on the nearest OHE mast using approved legend.
• Vicinity of Substations and OHE Stations:
  • Traction Substations:
    • Lay cables at least 1 meter from metallic bodies and substation earthing systems.
    • Utilize concrete pipes or brick channels for 300 meters on either side of the substation.
    • Prefer laying on the track side opposite the substation.
  • OHE Switching Stations:
    • Lay cables at least 1 meter from metallic bodies and 5 meters from station earthing.
    • The 5-meter distance can be reduced to 1 meter if the cables are laid in concrete piles.
  • OHE Structures: Lay cables at least 1 meter from independent earthings for OHE structures.
• Cable Laying Outside Stations: Maintain a standard distance of 10 meters from the center of the nearest track.
• Signaling and Telecommunication Cables:
  • Maintain 100 mm distance between signaling and telecommunication cables in the same trench using bricks at 2-meter intervals.
  • Do not lay HT/LT power cables and telecommunication cables in the same trench.
• Cable Depth Relative to Track: Lay cables parallel to the track at 1.0 meter depth, and across the track at 1.0 meter below rail flanges.
• Power and Telecommunication Cable Trench Spacing: Keep power and telecommunication cable trenches as far apart as possible.
• Special Laying Conditions: Follow approved methods for laying cables along girder bridges, over culverts, through culvert beds, over rocky terrain, etc.
• Cable Bends: Avoid sharp bends. Minimum bending radius should be 40 times the cable diameter for aluminum-sheathed armored cables.
• Laying OFC and Quad Cables: Usually laid in the same trench, refer to Chapter XIII for drawings and specifications.

Cable Planning

• The number and size of conductors, and the type of cable required should be determined first based on the type of circuits desired.
• Zonal Railway may issue an allocation of quads, BPAC/IBS, etc. on the 6Q.
• Leave 25% or more conductors spare for all cables carrying 5 or more pairs of conductors for future expansion.
• Cables should be laid within 1 meter inside the Railway boundary, 2 meters away from the nearest track and beyond the embankment.
• Consult with P.Way staff before digging trenches near the formation area of the track.
• Fill in trenches and ram them after laying the cables on the same day before sunset.
• Ensure trenches are at least 1 meter away from electrical power cables.
• Cable markers should be provided every 50 meters along the route.
• Use a Quad cable RCC route marker as per Drawing no. RDSO/TCDO/COP-22(a) available at chapter XIII.
• Paint the markers red and use yellow enamel paint on all sides of the RCC cable marker above ground to identify quad joints.
• Cable should be buried at least 1 meter below the surface of the ground.
• Ensure the trench is wide enough for smooth cleaning and laying of cables.
• In yards, maintain a minimum distance of one meter between the cable and the OHE mast, and ensure the cable is laid in concrete pipes when this rule is difficult to observe.
• When the depth of the cable trench exceeds 0.5 meters near OHE masts, ensure the nearest edge of the cable trench is at least 3 meters away from the OHE mast.
• Mark the position of cable joints on the nearest OHE mast by painting an approved legend.
• When laying cables in the vicinity of traction substations, OHE switching stations, and their associated earthing system, ensure the cable is laid at least one meter away from any metallic body of the station which is fixed in the ground.
• Ensure the cable is laid at least one meter away from the substation earthing.
• Lay the cables in concrete pipes or enclosed brick channels for a length of 300 meters on either side of the substation.
• Lay cables on the side of the track opposite the substation side.
• Ensure cables are laid at least one meter away from any metallic body of the OHE switching station which is fixed in the ground.
• Lay cables at least 5 meters away from station earthing.
• The distance of 5 meters from station earthing can be reduced to one meter if the cables are laid in concrete piles.
• Ensure cables are laid at least one meter away from the independent earth provided for an OHE structure.
• Outside station limits, the cable should be laid a standard distance of 10 meters from the center of the nearest track.
• When laying signalling and telecommunication cables in the same trench, maintain a distance of about 100 mm between them by placing bricks at intervals of two meters.
• Do not lay HT and LT power cables and telecommunication cables in the same trench.
• When cables are laid parallel to the track, ensure they are buried at a depth of 1.0 meters.
• When cables are laid across the track, ensure they are buried one meter below the rail flanges.
• Keep the trench for telecommunication cables as far away as possible from the trench for the power cables.
• For laying cables along girder bridges, over culverts, through the bed of culverts, over rocky terrain, and other such locations, lay the cables as per approved methods for each location.
• Do not subject cables to sharp bends.
• Ensure the bending radius for the cable is at least 40 times the diameter of the cable in case of aluminium sheathed armoured cables.
• OFC and quad cables can be laid in the same trenches.
• Refer to chapter XIII for drawings on laying OFC/quad cables.