Dartford Tunnel LV

Customer: Highways Agency

Site Owner: Le Crossing

Value: £770k

FSD have a long history at Dartford and were awarded the contract to install new power cabling for the West Tunnel distribution panels.

All cabling and support systems were installed within the tunnel invert which was designated a confined space, consequently, a rigorous methodology of safe working had to be adopted, taking into account the limited headroom.

The consultants on the project were Jacobs Babtie in Maidstone, with whom we have worked previously on a number of projects at Dartford.

New cabling was installed for supply to the lighting, tunnel services and tunnel emergency telephones in the West Tunnel. The supplies were run in the invert under the road in the west tunnel connecting to junction boxes which in turn fed the Electrical Distribution Panels (EDPs) that were positioned road side. In order to break through the precast concrete invert wall to get to the EDPs it was necessary to undertake concrete drilling and sawing works.

Once the new cabling had been installed and tested the existing telephone cables were removed, tunnel services and lighting supplies were capped and left in position for possible re-use.

Our works on this project included:

  • New cable support systems throughout the invert, including a 1400m straight run of galvanised steel ladder rack
  • Installation of fire resistant IP67 power distribution boxes
  • New telephone cabling and distribution
  • 4200m 4 core 120mm power cable for EDP feeds
  • Modifications to EDP’s to allow auto-changeover on loss of supply
  • Modifications to main LV distribution boards