Others were less understanding.
“Once again, French civil servants are making things worse,” said Laurent Damour, en route to London for a few days of vacation. Mr. Damour said that customs officers were using Brexit as an excuse and creating dysfunction on top of existing problems. “We already know that Brexit is going to be a mess, thanks for reminding us,” he said.
With so much uncertainty surrounding the nature of Britain’s withdrawal from the European Union, there has been particular scrutiny in France on the readiness of entry and exit points.
A top official in northern France, Michel Lalande, warned last fall that security controls for passengers crossing the Channel might take twice as long, and some authorities have expressed concern that infrastructure for veterinary or plant controls might not be ready by the end of March.
As the deadline looms, however, the French government says that — barring some minor hiccups — the transition will be frictionless.
“Customs agents are crying out before any actual pain,” said Rodolphe Gintz, the director general of the French customs service. “Brexit isn’t here yet, and when it comes, we will be ready, because we have been preparing for this for almost two years.”
Little will change for private passengers, Mr. Gintz said, because Britain is not part of the Schengen area that largely abolishes border controls among many European nations. He said that the lines at Gare du Nord, where checks are already in place for Britain-bound travelers, would not be as long as the unions claimed.
The passage of goods could face more changes, though. If there is no deal, companies might have to declare their merchandise before the crossing to Britain, which would almost certainly cause costly delays.