Automatic Incident Detection
The main technologies used for incident detection in tunnels are:
- Distributed Temperature Sensors (DTS)
- CCTV with Visual Analytics
- Infrared CCTV
In the Dartford tunnels a fibre optic DTS system measures temperatures for every metre of tunnel and alarms on high temperatures or high rates of change of temperature.
CCTV signals from fixed cameras at 50m intervals throughout both tunnels are analysed to generate alarms on stopped vehicles or smoke.
A combination of high temperature and smoke in the same zone triggers a count down to automatic deployment of the water mist fire suppression.