MOTORISTS using the Saltash Tunnel are being warned of overnight disruption on Monday and Tuesday (April 20-21) this week as engineers continue critical testing of a new overhead lane control system.

National Highways confirmed safety checks on the upgraded signalling network will take place overnight from 7.30pm to 6am on Monday and Tuesday, as part of the ongoing modernisation of the key A38 crossing between Cornwall and Devon.

The latest phase of works will involve testing display symbols on the newly installed overhead lane signals, including red crosses, white arrows and green arrows. The checks are designed to ensure the system is operating correctly before it is brought fully into service.

During the testing period, traffic may be stopped briefly at temporary traffic lights to avoid confusion for drivers while the symbols are displayed.

Road users have been urged to ignore the overhead signals while the tests are underway, remain in their current lane and continue to follow existing traffic management measures. Electronic message boards will also carry reminders stating: “Testing overhead signals, stay in lane.”

Officials said testing of the new signals is expected to be completed in the coming weeks, paving the way for the tunnel’s tidal flow lane system to be activated. Advance signage will be displayed before the new reversible lane becomes fully operational.

The wider upgrade project at Saltash tunnel includes replacing ageing control technology that is nearing the end of its working life.

Other improvements include new LED lighting, upgraded power cables, replacement air quality monitors, a modernised ventilation system and new signs to keep motorists informed of conditions ahead.

The existing emergency “wig-wag” crossing is also being replaced with new traffic lights and automatic barriers designed to stop traffic quickly and open diversion routes when required.

The tunnel remains closed overnight from Monday to Friday while works continue, although National Highways said schedules may change if engineering activity overruns.

Once complete, the improvements are expected to reduce future closures by moving some equipment outside the tunnel for easier maintenance access, while improving safety and helping drivers plan journeys more effectively.

The Saltash tunnel is one of the South West’s most important road links, carrying thousands of vehicles every day.