Part of the M20 will shut tonight as part of Operation Brock preparations.
With the end of the Brexit transition period looming, a large section of the carriageway will close for four nights from 8pm.
'Live tests' of the new moveable barrier will be conducted each night between 8pm and 8am by Highways England until Tuesday morning.
The coastbound section affected will be between Junction 7 for Maidstone and Junction 9 for Ashford until 8am on Monday.
While Londonbound there be closures between junctions 9 and 8 from 8pm tonight until 8am on Sunday and again between 8pm on Monday and 8am on Tuesday.
Signed diversions will be in place with traffic told to leave the M20 at junction 7 for Maidstone and rejoining at junction 9 for Ashford, Highways England has published a map of the London-bound route and according to the authority's website the coastbound diversion will be the same.
The diversion will take an extra 50 minutes and 48 miles.
Click the enlarge button in the top right corner of the below map to see closures and diversions.
The trials are being carried out in preparation for the Brexit transition on January 1, and Highways England has said "Operation Brock needs to be active by December 31".
On top of the closures, Highways England confirmed in a letter from project manager Manish Somrah that it will also "need to close parts of the M20 on weeknights before the test to put out traffic management".
During the upcoming tests, the concrete barrier which forms a contraflow on the London-bound side will be installed and then removed.
Being carried out in partnership with the Kent Resilience Forum, the £55 million project is part of the Operation Brock system which will aid in possible freight backlogs into Dover.
When active, the system sees one side of the motorway used by HGVs heading to cross-Channel ports, with all other traffic restricted to the 50mph contraflow on the opposite carriageway.
Designed to limit disruption on Kent's roads if there are problems at the Channel ports once the Brexit transition period ends on December 31, Brock is an alternative to Operation Stack, which closed sections of the M20 completely.
First announced in February, the initial installation of the barrier began in September and has only just been finished with a month to spare before Britain leaves the European Union.
After the test, bosses say the motorway "will return to normal" by 8am on Tuesday, December 15, with the barrier returned to the London-bound hard shoulder, where it is currently based.
Highways England south east operations director Nicola Bell said: “We have again worked extensively with our partners in Kent and are confident that this test will provide a valuable dress rehearsal into the operation of our Kent-wide port disruption contingency measures.
"The test will help us to fine tune Operation Brock, finding ways to make the deployment quicker whenever the barrier is needed, whether it be in preparation for transition, or other disruption to cross-channel services.
“Operation Brock will keep Kent moving, and we thank road users in advance for their patience while the test is taking place.”
Transport Secretary Grant Shapps said: “Kent is a critical link to one of our busiest trade routes, and this state-of-the-art technology will ensure that we can keep the local road network moving.
“Testing this barrier now will ensure that if the system is needed it can be quickly and safely deployed, helping drivers get to where they need to be - even in the event of disruption at the end of the transition period and to assist with any other future disruption caused for any reason.”