Hauliers will need special permits to gain access to Kent as the Government confirmed controversial plans to create an "internal border" in an attempt to avoid post-Brexit gridlock.
Cabinet minister Michael Gove said the permits could help avoid queues of up to 7,000 trucks seeking to cross the English Channel after the UK leaves the single market and customs union at the end of the year.
The Kent Access Permit (KAP) system could be enforced by police or the use of cameras monitoring the number plates of vehicles entering the county at points such as the Dartford Crossing bringing freight from Essex.
Mr Gove, the minister responsible for preparing the UK for leaving the European Union's economic structures, set out the measure as he outlined "reasonable worst-case scenarios" that could emerge from January 1.
A lack of preparation for the end of the transition period could result in as many as 70% of lorries being turned back from France, with thousands of goods vehicles waiting up to 48 hours to reach Dover as a result of the chaos.
Mr Gove said the "smart freight" system was aimed at avoiding that level of congestion.
"That system has been developed, it's being shared with business and we want to make sure that people use a relatively simple process in order to get what will become known as a Kent Access Permit, which means that they can then proceed smoothly through Kent because they do have the material required."
If they do not have a permit, Mr Gove said that through "policing, ANPR (automatic number-plate recognition) cameras and other means" the Government would do its "very best" to ensure people in Kent are not inconvenienced.
When the KAP system was proposed in August, trade body Logistics UK warned it would "create an internal UK border by introducing Kent Access Permits, adding more red tape to the work which hauliers will be obliged to comply with".
Mr Gove set out details of the Government's worst-case assessment in the House of Commons, telling MPs: "The scenario builds on an estimate that only 50% to 70% of large businesses and just 20% to 40% of small and medium-size enterprises would be ready for the strict application of new EU requirements.
"In those circumstances that could mean between only 30% and 60% of laden HGVs would arrive at the border with the necessary formalities completed for the goods on board.
"They'd therefore be turned back by the French border authorities, clogging the Dover to Calais crossing."
He said the queues of "up to 7,000 HGVs in Kent" were likely to "subside" after businesses learned from seeing their cargo denied access to the continent.
"But it is clearly far better that everyone is aware now of what is needed to prepare rather than to face additional disruption next year," the Cabinet Office Minister said.
A Government survey suggested that only a quarter of businesses are "fully ready" for the post-Brexit arrangements, Mr Gove said.
Labour argued more could have been done to prepare for the start of the new customs arrangements.
Shadow chancellor of the Duchy of Lancaster Rachel Reeves said: "It is incredible that ministers are only now admitting to their plans to arrest British truckers for entering Kent without new travel passports.
"With just over three months to go, how are businesses meant to prepare amid this Conservative carnival of incompetence?"
Kent Police's Assistant Chief Constable Claire Nix said: "Kent Police participated in the consultation related to the Kent Access Permit and is continuing to engage with the Government and other partners within the Kent Resilience Forum on how it will be enforced.
"This forms part of our ongoing work to keep Kent moving in the event of traffic disruption following the end of the EU transition period."
Mr Gove's announcement came as the EU's chief negotiator Michel Barnier was in London for informal trade talks.
Downing Street warned time was running out to reach a post-Brexit trade deal which could be in place by the end of the year.
The Prime Minister's official spokesman said: "We do still believe that it is possible to get a deal but we need to make progress because time is obviously running out."
Boris Johnson has said he wants a deal done by the time of the European Council summit of the bloc's leaders on October 15.