Project Location: London
Client: Costain / Highways Agency
Start Date: 2008
Completion Date: 2009
Contract Type: Design and Build
Procurement method: Highways Agency OJEU
Project Construction Value: £75m
Services provided: Highways, Structural
engineering, M&E, Intelligent Transport Systems, Geotechnical
Design, Site Supervision
The original 470m long cut and cover Bell Common Tunnel
was constructed in 1985, as part of the M25
The tunnel is located in a rural location under Epping Forest
north east of London. The refurbishment project provides an
additional traffic lane in each direction and replaces life-expired
tunnel equipment, thereby reducing maintenance costs and
The tunnel refurbishment brings the tunnel up to European Tunnel
Directive standards and comprised the replacement of all
mechanical, electrical, operational and communication systems, and
the installation of passive fire protection.
Bell Common tunnel forms an important node on the M25 road
network. As part of the M25 widening rollout, Bell Common tunnel is
to be refurbished to accept four lanes of traffic (D4M) through
each bore (from the current three lane (D3M) provision). With
environmental constraints in mind, this will be achieved by making
better use of space rather than widening the existing tunnel.
Capita Symonds' role involved:
- Preliminary design for target cost and detailed design of all
civil, M&E and communications systems.
- Assisted with tender documents and prepared performance
specifications for the procurement of specialist electrical and
- Review of sub-contractor’s designs
- Site supervision of works.
Intelligent Transport Systems
Capita Symonds' ITS team were appointed, under an ECI
scheme, to prepare the detailed design for the tunnel and motorway
communications systems on the approach to, and through the M25 Bell
Common tunnel. The duties included design of the tunnel control
systems and specification of all system interfaces.
Capita Symonds technology team are working as part of a
multidisciplinary team to provide a tunnel and motorway
communications detailed design that conforms with all current HA
and European safety standards and tunnel design codes of
As part of the motorway communications upgrade the existing
signalling provision was designed in line with current HA standards
with the installation of new Message Signs. A resilient
longitudinal cabling, power and communications network was
installed to prevent loss of services to the East Regional Control
Centre in the event of a fire is included.
The tunnel communications detailed design also included the
design of the combined Tunnel Plant Monitoring and Control System
(TPMCS) which utilises an integrated fibre ring network to
communicate with, and control the various tunnel sub-systems.
Our design scope extended to include the design of the SCADA
tunnel control systems, provision of new ERT facilities and
provision of VAID and MIDAS. CCTV systems were refreshed to support
the improved monitoring systems. A study to determine the
feasibility of introducing low profile signs was undertaken.