Moveable barrier being installed on the M20
The M20 will be closed overnight while a new system is installed to tackle queues leading to the Port of Dover.
The moveable barrier will replace a fixed structure removed in January that had been installed to handle traffic created by a no-deal Brexit.
It will allow lorries to be held on the motorway in the event of disruption to cross-Channel ferries.
The concrete barriers can be deployed or removed as needed within hours, Highways England said.
The London-bound carriageway will close from 21:00 BST until 06:00 between junctions 8 and 9 until 11 September.
Overnight closures are also planned for 16 to 25 November.
The London-bound carriageway will be reduced to two lanes with a 50mph limit while the coast-bound carriageway will be limited to 60mph.
A permanent barrier was installed in 2019 as part of Operation Brock – the government’s plan to tackle queuing lorries in the event that a no-deal Brexit created delays at customs for freight.
The previous system, which used metal barriers, had taken weeks to install and remove, Highways England said.
It was removed after MPs backed the withdrawal agreement.