WORK on the major £25-million upgrade of the Saltash Tunnel is entering a new and critical phase, as National Highways fast-tracks the installation of advanced traffic control technology following the detection of faults in the existing system.

The 37-year-old tunnel, a vital link on the A38 in South East Cornwall, is undergoing a once-in-a-generation refurbishment to improve safety, reliability and efficiency. Since the project began in January, construction teams have been busy carrying out excavations, piling, and concrete works under a series of full and overnight closures.

Initial efforts have focused on preparing for four large gantries to be installed at the tunnel approaches. These gantries, each measuring eight by nine metres, will carry dynamic signage to provide real-time travel information. This stage required deep excavation – up to five metres – to lay secure foundations.

Although the overhaul of the Tunnel and Traffic Control System was originally scheduled for later in the summer, irregularities in traffic signal performance prompted National Highways to bring forward this part of the scheme. As a result, the existing tidal lane system has been temporarily deactivated and replaced with fixed lanes to ensure motorist safety.

Currently, two westbound lanes are open through the tunnel and across the Tamar Bridge, with a single eastbound lane maintained for traffic heading into Plymouth. An additional cantilever lane is being used for local vehicles and Tamar Tag holders. The overhead signals remain on for now but will be switched off when the gantries are powered down.

To support the new traffic arrangements, extra safety measures have been introduced. These include newly installed traffic signals on the eastbound approach to the tunnel, the bridge, and tunnel entrances. Though not in constant use, these signals are ready to assist in emergencies or breakdowns.

National Highways has confirmed essential safety systems, including CCTV, remain fully operational throughout the works. Overnight closures continue as needed, with diversions via the B3271 and North Road clearly signposted.

As part of the wider project, 31 miles of copper cable and 12 miles of fibre-optic cable are being laid, relocating system infrastructure from inside the tunnel to external service buildings. This shift is designed to minimise future disruption and reduce the need for future closures.

The next stage of the project will run through summer and autumn and includes the installation of new signage, lighting, barriers, and upgraded ventilation and sensor systems to monitor air quality. Energy-efficient LED lighting and new cable duct covers will also be added.

Julian Mitchell, National Highways Tunnel Manager, said: “We’re doing everything we can to minimise disruption for users of the tunnel and Tamar Bridge. We’ve implemented the new traffic management now for safety reasons – and have planned this carefully with our partners and stakeholders.

“We appreciate the tidal flow switch-off will have an impact on people’s journey times, although our current monitoring suggests only slight delays. We advise people to plan ahead and allow extra time for their journeys.”

The upgrade is expected to be completed this winter, ensuring the Saltash Tunnel remains fit for purpose for years to come.