Tunnel's tidal flow upgrade set to go live
National HighwaysAn upgrade to a tunnel which carries up to 40,000 cars travelling between Devon and Cornwall every day is set to go live on Tuesday.
A major refurbishment scheme by National Highways to bring systems in the 38-year-old Saltash Tunnel up to "modern standards" was started in early 2025.
The work on the A38 tunnel includes an upgrade to the reversible tidal flow lane control system which is used to change the direction of one or more lanes to meet traffic demands on the Tamar Bridge.
National Highways said the upgrade was "essential to make the tunnel fit for now and for the future".
Over the past year, contractors have been working to install new signs and 31 miles (50km) of cabling.
The three-lane tunnel, which carries between 38,000 and 40,000 vehicles between Devon and Cornwall daily, would be able to manage traffic flow during the busiest times, National Highways said.
National HighwaysNational Highways said the reversible tidal flow lane system could be operated in tandem with the Tamar Bridge control room.
"Our systems have been operating for 20-plus years, so it's essential that we make the tunnel fit for now and for the future," said National Highways' tunnel manager Julian Mitchell.
"We're now nearing the completion of this generational upgrade, one which has presented a significant challenge and involved a complex operation."
National Highways said as part of the upgrade, the old bi-directional management was switched off last May, and following rigorous off-site testing and operational testing in recent weeks, the new system would go live before the morning peak time on Tuesday and in advance of the anticipated summer increase in vehicles.
As part of the switch-on, the westbound 30mph speed restrictions from Carkeel roundabout are to be removed and returned to 50mph, National Highways said.
Correction 18 May 2026: In an earlier version of this article the headline and the copy originally said the tunnel's upgrade was a European first. This was incorrect so we have amended it to remove this reference. The article has also been updated to make it clear the upgrades are part of a major refurbishment scheme.
