Dartford free-flow crossing plan images released
Artist's impressions showing a proposed layout at the Dartford Crossing after the introduction of a free-flow charging system have been released.
Work will begin in spring with the new payment system due to come into operation in October on the crossing between Kent and Essex.
Drivers will be able to pay online, by SMS text message or by phone.
Lights and barriers will be used on the northbound approach to the tunnels to control traffic volumes.
Vehicles will be recorded via number plate recognition cameras.
Payments will be accepted in advance, and up to midnight on the day after crossing, a Highways Agency spokeswoman said.