Vacationers in French ski country faced a traffic jam that covered 50 miles, while railway officials said they were braced for a million train passengers.
The annual French winter holiday for students in Paris and Bordeaux is a popular time to hit the Alps for some skiing, but it was delayed for many who sat in traffic instead. Particularly bad was the A43 between Lyon and Chambery, the heart of ski country.
Air quality alerts were posted in the region due to the heavy traffic.
Those seeking to return from the Alps faced 25 mile delays, Radio France Internationale said.