No major accidents had been reported by Sunday, and traffic volumes were still normal, but major delays were expected on Monday and Tuesday, said Thato Mosena.
Traffic volumes were expected to increase again next Tuesday, just before New Year, and again on January 5 and 6, when people were expected to return from their holidays.
Mosena said a high traffic volumes were experienced when 1000 to 2000 or more vehicles an hour were travelling on a route.
She said more than 2000 vehicles an hour were expected during peak holiday times.
The N1 north between Pretoria, Polokwane and the BeitBridge border post was expected to be busy, as was the N2 to and from Somerset West and Cape Town.
A lot of traffic coming into Durban from Johannesburg was expected on the N3.
High volumes of vehicles travelling on routes between Mangaung and Cape Town and between Pretoria, Nelspruit and Lebombo were also expected.
N3 Toll Concession spokeswoman Andy Visser said on Sunday morning that about 1000 vehicles an hour had been heading out of Gauteng at the tollgates.
About the same number of vehicles was heading out of KwaZulu-Natal, but more, at 1100, were entering the province.