A new traffic system that identifies vehicles which pose a safety risk has been installed at the Dartford Crossing.
Oversized HGVs and hazardous loads travelling northbound from Kent into Essex will be turned around before they enter the tunnel.
The new safety system will automatically identify restricted vehicles and set off a series of traffic signals and barriers.
Vehicles will then need to be re-directed into a separate lane where they will be met by an escort and taken through the tunnel.
If you are carrying hazardous goods or abnormal loads you must report to the vehicle marshalling area to be checked before using the tunnel.
Vehicles transporting hazardous goods, or those which exceed the size restrictions shown below must exit at Junction 1a and follow the ‘hollow diamond’ symbol to the vehicle marshalling area, to be checked before using the tunnels.
Drivers who fail to follow the new signs and use the correct lanes could face fines or even points on their licence.
This is all part of the Dart Charge scheme where crossing tolls are now paid for online.
Previously, unsuitable vehicles were identified by staff in their toll booths, now that the toll booths have been replaced by a free-flowing charging system this new system has been put into place.
Dart Charge project director Nigel Gray said drivers would need to take extra care due to the significant change to the road layout.
"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," he said.