Work to move a motorway barrier built to ease post-Brexit traffic disruption near Dover will cause delays of up to a year.
National Highways said there will be lane closures and a reduced speed limit on the M20 between junctions eight and nine from the end of this month until at least October as a barrier that helps traffic flow during delays in the English Channel is moved.
Operation Brock is a reverse flow system that allows vehicles bound for the Port of Dover or the Eurotunnel terminal in Folkestone to queue on the motorway while allowing other traffic to continue in either direction.
It uses a moveable concrete barrier that can be deployed overnight.
The barrier was first deployed in December 2020 but is currently stored on the hard shoulder.
National Highways plans to move the barrier to the median.
Meanwhile, speed limits will be lowered to 50mph along the 13-mile route.
There will also be several night closures.
The roads authority said the work, which includes a “comprehensive” drainage improvement and new signage, is being carried out in phases and could take “up to 12 months”.
Steve Gooding, Director of engine research organization RAC Foundation, said: “Drivers using the M20 corridor will be dismayed at this latest news, which comes after years of disruption from a number of major projects, including the initial installation of the accessible, intelligent highway upgrades and the construction of Junction 10A.
“Users of the M20 might legitimately ask whether this latest work could have been carried out when the barrier was first erected, why it is taking so long and what is being done to minimize disruption during the work.
“The M20 is clearly having to deal with a unique range of stresses, but all driving this key stretch must fervently hope that this is the last in a long line of disruptive work and will be the last for the foreseeable future.”
Operation Brock was meant to be a temporary measure when it began in 2020 but was revived in July.
Emergency Traffic Management powers were due to expire in October but were made permanent.