Almost 5,000 metres of cable will be installed inside the tunnel to provide a quicker detection of incidents, starting on Monday 26 November.
The new technology will include Wayfinder emergency evacuation signs, and separate smoke and heat detection systems, all aligned to the public address system to direct drivers to the safest tunnel exit in the event of an incident.
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The new installations support the tunnels safety history, after a new PA and CCTV system was installed two years ago.
Highways England spokesman Julian Strong said: "The current detection system is still operational but this essential upgrade is needed to meet current standards, and the work to integrate the different systems is innovative.
"This will enable automatic detection, without the risk of false alarms, and make the tunnel as safe as possible for all those who use it.
"The installation and connection of the cable is a complex procedure, the work will take place under overnight closures to minimise its impact on people, and we apologise in advance for any disruption."
The work will be completed in spring 2019.
(CM/MH)
