CASE STUDY: London’s HE – this series of work included the M25 Holmesdale, Bell Common, nearby Hatfield tunnels and TfL’s Blackwall tunnel.

““the M25, A1 (M), and Blackwall Tunnel refurbishment, major infrastructure refurbishment projects and upgrades in a live environment with minimum disruption to operation”


PDS have subsequently provided routine maintenance and call out support to these tunnels. We have expanded our service capability and in addition to SCADA and control systems we now include radio systems, linear heat, UPS, VAID, and more recently we have enabled the trial of RADAR units for stopped vehicle detection on the M25.

The M25 Holmesdale road tunnel needed a full refurbishment and upgrade which included the addition of Saccardo ventilation requiring complex fan control, and the addition of extra lanes. Our scope included the fast-track refurbishment and upgrade to Tunnel Plant Monitoring & Control Systems, interfacing to other traffic management and traffic systems, and the provision of the PA (Voice Alarm) System. Overall project goals included the minimising of long-term impact on M25 traffic, and this resulted in a shortened overall project programme and accelerated commissioning activities. This was supported by PDS’ integrated systems approach where systems are assembled, integrated and subject to in-depth testing in the factory before deployment to site, thereby optimising and de-risking the site programme. The tunnel was re-opened on 3rd September 2007 “three months early”.

The Bell Common Tunnel, with similar works, was undertaken and reopened early and under budget in March 2010. This project also including our unique SCANLIGHT dimmable lighting solution, in preference to a competitor system installed in Holmesdale.

Then the A1 (M) Hatfield Road Tunnel project to refurbish the legacy electrical and mechanical equipment and upgrade the tunnel in line with new standards. Our scope was to design and supply a tunnel control system including subsystems such as a fully integrated SCADA, communications network, CCTV, Video Incident Detection, Radio, Telephones, PA, Lighting and Fire Detection systems, and includes PDS’ dimmable SCANLIGHT tunnel lighting control system. The project was engineered with the latest development of the PDS MATRICS IP solution where video, audio and plant data are managed and presented through an integrated user interface. The unique challenge was to implement the refurbishment project against a very tight programme with minimum impact on live motorway traffic, this was achieved and the tunnel was fully reopened in May 2011.

In parallel with the above projects we were also involved in the Blackwall Northbound Road Tunnel covering the refurbishment and upgrade to Tunnel Plant Monitoring & Control System, with all work carried out during night time closures to this central London strategic transport route to allow busy central London traffic to use this strategic transport route during the day. The tunnel was successfully completed and “reopened” early to contract in the summer of 2011.

A supported approach.

At PDS our philosophy is to support you from the initial concept through all stages of a project, and to be able to continue that support through asset life, servicing every aspect of your needs from our own team or with our partner companies.

Contact our expert team