More than 100 lorries will gather at a disused Kent airfield today as part of rehearsals for how Britain's roads will cope if there is a "no-deal" Brexit.
The vehicles will test Manston airfield as a mass HGV holding bay to ease congestion on roads to Channel ports in the event the UK leaves the EU without an agreement.
Congestion at the ports caused by customs checks being reintroduced on goods is cited as among the negative effects of a no-deal withdrawal from the bloc.
The trial is part of the government's plan to prepare for the possibility of the UK leaving the EU without a deal at the end of March.
Under Operation Brock, the lorries plan to leave the airfield around 8am, drive down to Dover in the rush hour and then come back again.
Around three hours later, they will be asked to do it all over again.
The drivers are contracted by the Department for Transport (DfT).
Dover is one of the key points of entry to the UK and the idea is to see whether it is possible to integrate a fleet of lorries into the traffic around Manston.
That is because there are plenty who fear that delays caused by a no-deal Brexit would see thousands of lorries backed up in all directions.
And one solution is to park a number of them, temporarily, at Kent's one-time airport.
The plan is to "establish the safest optimum release rate of HGVs" from the airfield to Dover along the A256.
A DfT spokeswoman said: "We do not want or expect a no-deal scenario and continue to work hard to deliver a deal with the EU.
"However, it is the duty of a responsible government to continue to prepare for all eventualities and contingencies, including a possible no deal.
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"We will be testing part of Operation Brock to ensure that, if it needs to be implemented, the system is fully functional."
Also known as Kent International Airport, Manston closed in 2014 after owners could not find a buyer.