Operational Details

Supervisory Control and Data Acquisition (SCADA system) is the heart of the tunnel management whose priority is the safety of users and the efficient use of the facility.

The tunnel is ventilated by 24 jet fans suspended above the carriageway. These are automatically activated via the SCADA system by carbon monoxide and visibility monitors.

Lighting is provided by fluorescent tube luminaire but to allow drivers to quickly adjust their eyesight to conditions when entering the tunnel, lighting levels are boosted in the portal areas by high pressure sodium luminaires, automatically controlled by external photocells linked to the SCADA system

In the event of mains failure, uninterruptible power supply units and a generator will start up automatically to continue supply.

The environment within the tunnel is continuously monitored for both traffic control and safety reasons. Any traffic congestion or incident will activate alarms on the SCADA system in the tunnel management building situated at the northern side of the tunnel, adjacent to the Dunkettle interchange.

Where necessary, traffic can be directed to share one bore (Contra flow) or the tunnel can be closed completely by way of variable message signs on both approach roads.

Evacuation of the tunnel can take place through a Central Service/Emergency Escape Passageway, access to which is provided every 100 metres.

Should a driver need assistance emergency telephones are provided at 50 metre intervals along each traffic bore.