National Highways will be embarking on the second phase of a major modernisation upgrade of the A38 Saltash Tunnel later this autumn.
As part of a ‘generational’ refurbishment project, the Tunnel and Traffic Control System within the 36-year-old tunnel will be upgraded, including electrical distribution, new LED lighting, fans and electronic signage.
Carrying around 40,000 vehicles a day, the 410-metre long, three-lane bi-directional structure is the only tunnel in Europe operating by tidal flow.
As such, the tidal flow corridor relies on specialised technology, and the £25 million modernisation programme is essential to maintain the safe operation of the tunnel for many years to come.
The current tunnel and lane control system is over 20 years old, approaching the end of its life and is being replaced and upgraded as part of an extensive programme of work, which will maintain safety within the tunnel, provide more reliable journeys and reduce the risk of unplanned closures.
Initial preparatory work, including the stripping out of old cabling, has been taking place since last autumn, in tandem with a speed reduction scheme which saw the speed restriction lowered from 70mph to 50mph between the tunnel and Carkeel roundabout.
New average speed cameras have also been installed to enforce the 30mph limit through the tunnel and on the B3271 and North Road diversion routes.
And as part of its commitment to safety and air quality, National Highways’ upgrade work will see:
Renewal of the tunnel control and traffic management system;
New, energy-efficient LED lighting;
Fibre cabling as part of a modern electrical power distribution system;
Modernisation of the ventilation control system to manage air quality;
The replacement of existing sensors to improve air quality monitoring;
The installation of traffic signals and automatic barriers to improve safety in the event of closures and emergencies;
Improved information signage and messaging;
the installation of easy-access cable duct covers.
Julian Mitchell, National Highways’ Tunnel Manager, said: “The tunnel is safe but it is essential that we replace our systems which have been operating for 20-plus years, to make the tunnel fit for now and for the future.
“The tunnel and the tidal flow corridor rely on specialised technology to operate and keep our customers safe, there’s been a considerable amount of planning over several years to identify efficiencies and bring the tunnel’s systems up to modern standards, and ultimately this will reduce the number of future maintenance closures.”
The programme of work is expected to take 12 months to complete, and will start in late November.
Saltash Tunnel will be closed overnight, on week nights only, from November until autumn 2025, with drivers using the standard B3271 and North Road diversion routes during the 8pm-6am closure
Between November and spring 2025, the inner westbound lane of the A38 will also be narrowed between St Budeaux and the Tamar Bridge roundabout, to enable working space for the installation of sign foundations.
And from the spring until scheme completion, the tunnel and bridge will no longer operate on a tidal flow basis, with fixed lanes in operation and clear directions for each lane.
The Tamar Bridge will retain its four traffic lanes, and until the start of the summer holidays, there will be one lane fixed in each direction for A38 traffic, a lane dedicated for Saltash town only in the westbound direction and the eastbound cantilever open for local ‘tag only’ traffic.
Mr Mitchell said: “The tunnel forms a key route between Plymouth and south east Cornwall, and any work has to be carefully planned with our Tamar Bridge partners and other stakeholders.
“We appreciate the scheme will have some impact on road users and Saltash residents, but we’re keeping the closures to an absolute minimum and we thank all drivers and residents in advance for their co-operation and patience ahead of starting work on this generational upgrade.
“Being a bi-directional tube with three lanes and tidal flow, and connecting directly to the Tamar Bridge, the tunnel is unique, and it’s difficult to work safely within the structure without closing it overnight.
“We’ll be keeping local communities informed ahead of start of work and in the meantime, we advise people to prepare, plan ahead and consider a little extra time for their overnight journeys.”
For more details on the scheme and National Highways’ other work in the South West go to https://nationalhighways.co.uk/our-work/south-west/
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