M25 Bell Common Tunnel Refurbishment

The M25 London Orbital Motorway is a fundamental component in Britain’s motorway network designed to allow traffic to bypass London. Since its completion in 1986 it has become one of the busiest motorways in Europe. The northern section, where the Bell Common Tunnel is situated between the M11 and Waltham Cross, experiences traffic flows of over 120,000 vehicles per day. The Bell Common Tunnel is a 550 meter long cut and cover tunnel consisting of two parallel bores aligned approximately east to west.
Bell 7
The purpose of the project was to upgrade the tunnel 2 lanes available ready for the widening of the M25 and refurbish the tunnels mechanical and electrical equipment which had reached the end of its design life and becoming beyond economic repair. Work began in June 2008 and was opened up for 70mph two months early in March 2010.

VVB were appointed by the main contractor, Costain to supply the labour and engineering services required to complete the electrical and mechanical installation elements of the project.

Our involvement ranged from assisting with design, procurement and supplier selection to installation, testing and commissioning.

Our works included:

  • Installation of HV transformers
  • LV electrical switch gear and distribution network
  • Emergency standby generator
  • Replacement of tunnel lighting system
  • Saccardo nozzle tunnel ventilation
  • Replacement of tunnel fire main including booster pump and water storage tank
  • Tunnel Plant Monitoring & Control

System (SCADA system)

  • Video Incident Detection system (VID)
  • Radio Re-Broadcast System
  • Tunnel Public Address System
  • Cross Passageway Doors
  • Motorway communications hardware upgrades: CCTV, MIDAS, traffic signals, emergency roadside telephones and NRTS longitudinal communication cables
  • Building services: Intruder alarm, fire alarm, fi re suppression, local CCTV, maintenance telephones and access control
  • Temporary HV and LV power distribution and site setup
  • Temporary fire safety system – fire main
  • Temporary tunnel safety systems: SCADA, gas monitoring, public address, telephones and ventilation