The M25 Orbital is a fundamental component in Britain's motorway network, enabling traffic to bypass London. It is one of the busiest motorways in Europe. Its Northern section - home to the Bell Common tunnel - experiences traffic flows of over 120,000 vehicles a day.
Installation, Maintenance and Testing and commissioning
£10 - 20 million
The Bell Common Tunnel is a 550 metre long ‘cut and cover’ construction, consisting of two parallel bored tunnels, aligned approximately East to West.
This project was required to upgrade the tunnel ready for the widening of the M25, and refurbish Mechanical and Electrical equipment, which had reached the end of its design life and was beyond economic repair.
VVB was appointed by main contractor, Costain, to assist in design and supplier selection, as well as installation, testing and commissioning of Mechanical, Electrical and Communications systems. Once established, VVB maintained these systems for the duration of the programme.
Throughout the refurbishment project, we managed our own Mechanical, Electrical, Communications, System Compliance (MECSC) process which, together with the technical working group, enabled an 8.5% improvement on delivery.
Temporary and Enabling systems
VVB delivered site setup, temporary HV / LV power distribution, lighting, fire safety systems and tunnel safety systems, SCADA, gas monitoring, PA, telephones and ventilation.
Scope of works
Our scope involved assisting in design and supplier selection for the installation, testing and commissioning of Mechanical, Electrical and Communications systems, and their maintenance for the duration of the programme.
Specifically, VVB delivered:
- HV transformers
- LV electrical switch gear and distribution network
- An emergency standby generator
- Replacement of the tunnel lighting system
- Saccardo nozzle tunnel ventilation
- Replacement of the tunnel fire main, including booster pump and water storage tank
- A Tunnel Plant Monitoring and Control System (SCADA system)
- The Video Incident Detection system (VID)
- A Radio Re-Broadcast System
- Tunnel Public Address System
- Cross Passageway Doors.
We were also responsible for motorway communications hardware upgrades including CCTV, MIDAS, traffic signals, emergency roadside telephones and NRTS longitudinal communication cables.
Building services supplied by VVB include an intruder alarm, fire alarm, fire suppression, local CCTV, maintenance telephones and access control.