The energy-efficient lighting solution will result in energy savings of over 1 million kWh per year, a 63% reduction, which is equivalent to the energy bills for over 340 homes per year.

The tunnel lighting replacement project presented a significant opportunity to lower the Authority’s energy consumption, carbon footprint and in turn, reduce maintenance and electricity costs. The previous lighting system had passed it’s designed life span and maintenance work and costs had been increasing year on year just to keep the lights on.

The tunnel was predominately lit with old fashioned fluorescent tubes containing the hazardous substance Mercury. Forthcoming changes in law, will effectively ban the sale of these lamps going forward, which would have created further maintenance issues if not upgraded. The newly installed LED system will massively reduce maintenance works and running costs for Kent County Council. Having worked to a tight programme to ensure minimal disruption to the local community and road users, Bouygues E&S’ expert teams worked 24/7 for the duration of the project.

The works involved the removal and recycling of all existing lighting systems and cabling along with the associated steel work and control systems, and the installation of new stainless steel suspension systems and cable trays as well as the latest and most efficient LED lighting technology.

The installation was controlled by a completely new state of the art lighting control system incorporating Luminance meters (photometers), an RS-485 duplex communication system running throughout the tunnel connecting the DALI controlled lighting to the existing overall tunnel SCADA control system. As part of these works, modifications and replacement to switchgear and electrical distribution systems were carried out including 14 tunnel distribution panels, 38 function units in existing LV switchboards and over 14km of power cabling including both AC and DC systems.

Additionally, the tunnel’s uninterruptible power supply (UPS) systems and battery storage facilities that are at the end of their design life have been replaced with an efficient and cost effective state-of-the-art UPS system.

Matt Fitzpatrick, Connected Cities Divisional Sales Director for Bouygues E&S’ said: ‘The Chestfield Tunnel lighting upgrade solution will play a key role in helping Kent County Council reduce it’s carbon footprint while providing a sound return on investment and reduced on-going maintenance costs’

Neil Baker, Cabinet Member for Highways and Transport, commented : “This has been an excellent project and a demonstration of how, with the right contractor and careful planning, a very satisfactory improvement to the asset can be brought about, ensuring its resilience and greater usability into the future.”