As part of a ‘generational’ refurbishment project, National Highways will upgrade the tunnel and traffic control system, including electrical distribution, new LED lighting, fans and electronic signage.
Carrying around 40,000 vehicles a day, the 410m-long, three-lane bi-directional structure is the only tunnel in Europe operating by tidal flow. This relies on specialised technology, and the £25m modernisation programme is essential to maintain safe operation of the 36-year-old tunnel.
The current tunnel and lane control system is over 20 years old.
Initial preparatory work, including the stripping out of old cabling, has been taking place since last autumn, in tandem with a speed reduction scheme.
And as part of its commitment to safety and air quality, National Highways’ upgrade work will include renewal of the tunnel control and traffic management system; new LED lighting; fibre cabling as part of a modern electrical power distribution system; modernisation of the ventilation control system to manage air quality; replacement of existing sensors to improve air quality monitoring; installation of traffic signals and automatic barriers to improve safety in the event of closures and emergencies; improved information signage and messaging; and installation of easy-access cable duct covers.
National Highways tunnel manager Julian Mitchell said there had been “a considerable amount of planning over several years” to identify efficiencies and bring the tunnel’s systems up to modern standards, which would ultimately reduce the number of future maintenance closures.
The work will start in November and is expected to take 12 months to complete.
