Motorists to see speed limits return to 50mph across major route after months of 30mph delays

However, the 30mph restriction remains in place through the tunnel itself and on the B3271 and North Road diversion routes.

National Highways said the changes were introduced ahead of the busy summer season, when traffic between Devon and Cornwall increases significantly.

The Saltash Tunnel carries around 38,000 to 40,000 vehicles every day and is one of the only tunnels in Europe to use a reversible tidal flow system. This allows traffic lanes to change direction depending on demand at peak times.

National Highways described the work as a "generational upgrade" of the 38-year-old tunnel.

The tunnel's bi-directional traffic system had been switched off since May 2025 while engineers carried out a major refurbishment programme.

Over the past year, contractors have installed new overhead gantries, laid 31 miles of fibre optic cable and upgraded electrical systems throughout the tunnel.

Four large external gantries measuring five by nine metres have also been installed to display live traffic information to motorists.

Another major part of the project is the replacement of the tunnel's old sodium lighting system with a total of 226 modern adaptive LED lights.

National Highways says the new lights are more energy efficient and should last more than 15 years, compared with the previous system, which needed replacing every four years.

The tunnel's east and west service buildings have also been modernised, with decades-old equipment removed and replaced with new electrical technology.

Other improvements include upgraded ventilation controls, environmental monitoring sensors, and new traffic signals designed to improve safety during emergencies or closures.

Julian Mitchell, National Highways' Tunnel Manager, said: "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."

He said the tunnel system works closely with the Tamar Bridge control room and depends on specialist technology that is now close to being fully operational again.

Mr Mitchell added: "We've done all we can to minimise disruption for local communities, and users of the tunnel and Tamar Bridge, we've been keeping all stakeholders informed every step of the way, and we thank people for their continued patience as we continue towards completion of the scheme."

National Highways said it had worked closely with Tamar Crossings partners throughout the project. Despite today's milestone, several months of work still remain before the full scheme is completed later this year.

Engineers still need to install new electronic message signs near Carkeel, Tamar Bridge, and Manadon. More fibre optic cabling, lighting upgrades, and power installations are also planned. The tunnel itself is still due to be resurfaced.

Drivers should also expect overnight closures from Monday to Thursday throughout the summer while crews safely complete the remaining work.

Mr Mitchell acknowledged the disruption caused by the project, saying: "Once fully completed, the upgrade will reduce the number of maintenance closures, and in the meantime, we thank all drivers and residents for their continued co-operation and patience."