Channel Tunnel

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Channel Tunnel
2
Principle Components

• Tunnel Structure
• Main running tunnels, 2 no. 7.6 m dia
• Service tunnel, 4.8 m dia
• Cross-over caverns (2 no.)
• to allow limited service during maintenance
  activities
• Piston relief ducts (at every 200 m)
• to allow pressure equalisation
• Cross-passages (at every 375 m)
• to allow access to service tunnel in case of an
  emergency, and
• provide ventilation and maintenance access

3
Principle Components

• Drainage System
• 5 pumping stations
• Drainage pipework
• Electricity communications
• Supply to caternaries (25 kV)
• Internal lighting and ventilation systems
• Voice Data communications

• Ancillary services
• Cooling system
• Fire-fighting system
• Ventilation system
• Track Traction System
• Running track directly connected to concrete base
  slab
• Catenaries supported from tunnel crown

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Environmental Conditions

• External
• Generally in dry chalk-marl.
• 3 km section French side in fractured clay
• Ground water saline
• Internal
• Nominally dry (rh 60 to 99)
• Running Temperature - without cooling 65ºC
• - with cooling 20-25ºC

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Tunnel Pipework

• Fire-fighting
• 100 mm dia wet main along both running tunnels
• 250 mm dia wet main in service tunnel
• Wet mains inter-connected at cross passages
• Total capacity 4,000 m3
• Cooling
• 450 mm dia pipework in both running tunnels
• Feed and return
• Total capacity 40,000 m3
• Drainage
• 400 mm dia pipework in service tunnel (up to 4
  no)
• Under track drainage to sumps at pumping stations.

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Cooling System Schematic
English Side
French Side
Cooling Pumping Stations
Under Land Section
Under Sea Section