Final phase begins on £25m Saltash Tunnel upgrade

National Highways has entered the final stages of a major £25 million upgrade to the Saltash Tunnel on the A38, a key route linking Plymouth with south-east Cornwall.

The 410-metre tunnel, which opened in 1988 and carries around 38,000 vehicles a day, uses a central reversible lane to manage traffic during peak and holiday periods. The current project aims to replace ageing control technology that has been in operation since the tunnel first opened.

According to National Highways, the main civil engineering works have now been completed. Contractor Taylor Woodrow has installed the final two gantries for the scheme – one west of the Carkeel roundabout and another east of the Manadon roundabout. In addition, 64 electrical cabinets have been installed and connected as part of the upgraded control system.

Foundation work for the new gantries was completed last summer by subcontractor Van Elle.

The wider programme, which began in early 2025, includes the installation of new LED lighting, upgraded power cabling and ducting, replacement air-quality monitoring systems, and a modernised ventilation system. New roadside signage is also being installed to provide clearer information to drivers about tunnel conditions.

A new traffic management system will replace the existing “wig-wag” crossing arrangement, introducing traffic lights that can halt vehicles in emergencies and allow diversion routes to be activated quickly.

Engineers will soon begin extensive electrical refurbishment at the tunnel’s east service building, where equipment dating back to the 1980s will be removed and replaced.

The new tidal-flow lane control system is expected to be activated in the spring, with the overall project scheduled for completion later in 2026 following a period of safety testing.

National Highways said it has worked closely with local authorities and stakeholders to minimise disruption. Upgrading operational tunnels presents particular challenges, as new systems must be installed and commissioned while maintaining safe traffic flow on one of the region’s busiest trunk roads.