A year of work to move the Operation Brock barrier from the hard shoulder of the M20 to the central reservation starts tonight.

National Highways is to shut the stretch between Junction 9 for Ashford and Junction 8 for Leeds Castle from 8pm until 6am tomorrow.

The motorway will be closed in both directions, with drivers advised to use the A20 as a diversion.

Contractors will be installing 'traffic management' during the closure, which marks the start of 12 months of works that are set to continue until January 2023.

The barrier, which is used to form the Operation Brock contraflow at times of cross-Channel disruption, has been stored on the hard shoulder since December 2020.

But Nicky Potts, National Highways head of operational integration, says it “was only a temporary measure” due to safety concerns.

“We are about to start work to move it onto the central reservation, its permanent home, which will allow the hard shoulder between Ashford and Maidstone to be reinstated to its original width,” he said.

“This involves extensive construction work along the 13-mile stretch which will take up to a year.

"It will be carried out in phases, moving from Ashford to Maidstone.

"Road users will see the barrier in place on the London-bound M20 but it will be used as a safety barrier.

“If there is a reason to use the contraflow system as part of Operation Brock, it can still be easily deployed.”

But Ashford MP Damian Green says he shares residents' concerns about the length of the closure.

"National Highways says it is doing more than just moving the barrier but I still question why it's taking that long," he told KentOnline this week.

"I would still like to see other work done between Junction 8 and 9 because a lot of people want to see resurfacing work to make the motorway quieter.

"That's not something they've mentioned so I will be pressing them on that."

From Saturday, highways bosses say lane closures will be needed on both carriageways "for approximately 40 weeks".

On the London-bound side, the two outside lanes will be shut, with work starting at the Ashford end of the motorway.

The hard shoulder will be in use, so there will be two lanes running London-bound, and a 50mph speed restriction will be in place.

On the coastbound carriageway, the outside lane will be closed, but bosses say they will "aim to only close the section of road where work is taking place".

A "small number" of further overnight closures of the M20 will also be required, according to National Highways.

Last week, the roads authority issued a bullet-point list explaining why the works will take a year following questions from KentOnline.

It says it will include:

1. Upgrading the central reservation to store the barrier

2. Permanent signage and posts

3. Permanent vehicle restraint system barrier

4. Upgrading an existing welfare area

5. Upgrading the drainage including the Junction 9 pond storage area

6. Upgrading the existing CCTV system

In a statement on its website, National Highways added: "Wherever possible we’ll tell you in advance if we need to close the road overnight.

"There may, however, be occasions due to unforeseen circumstances, for example safety critical emergency work, where we may be unable to publicise closures in advance.

"Similarly, our dates are subject to change in the case of adverse weather or other unplanned events."

To sign up for alerts about the work, email M20MoveableBarrier@highwaysengland.co.uk