The safety system to identify vehicles which may be a safety risk will go live on the weekend of 13-14 June.
The system will automatically work out which vehicles need to be stopped and either turned around or which need to be escorted through the tunnel. These include over-height lorries and those with dangerous loads.
Despite the charging of vehicles being automatic since last November, those travelling north through the tunnels have still had to slow at barriers because this was the only way that they could be checked for safety reasons. Now a new automated system will mean it will be free-flow like southbound traffic over the bridge.
Dart Charge project director Nigel Gray said: “Since Dart Charge launched in November it has already significantly improved journeys at the Dartford Crossing. This new safety system is vital for the safe operation of the tunnels and will enable us to remove the old payment barriers for good. It will mean a significant change to the road layout, so I advise drivers to take extra care and pay extra attention to all signs and signals, especially for the first few times they use the crossing following the change.”
Final road layout changes will be complete later this summer.