From the last Saturday in July to the last Saturday in August, there is an additional driving ban on Saturdays from 07:00 to 19:00 and on the following Sundays from 00:00 to 22:00 for trucks and road trains exceeding 7.5 tonnes of gross vehicle weight on all roads, as well as for vehicles carrying dangerous goods, regardless of their weight. (On these Saturdays, driving is allowed from 19:00 to 24:00!).
There is an exception to the driving ban on Sundays and public holidays for travel to/from the port of Calais (the so-called Corridor de Givelès). This only includes the A 16 from Calais to Belgium (De Panne border) and back, but not the A 26 and A 27. This exception does not apply to the transport of dangerous goods. This exemption applies in both directions for vehicles travelling between the UK and Belgium (this means an international service which actually uses a ferry).
General traffic ban on Saturdays and the eve of public holidays from 22:00 to 22:00 on Sunday or the public holiday itself for vehicles over 7.5 tonnes on all roads. And also on Saturday (public holidays) and the Sunday before a public holiday from 00:00 to 24:00.