If you’ve driven through open range land, you would know what these are. Apparently they’re named after Canadians in France.
Basically, it’s a term for the metal rods in the road that stop cows passing through. On my favourite climb in the 2012 Tour - Col du Grand Colombier - there is not much up top except several barrières Canadiennes on each side.
Apparently, a Potluck dinner is called a Picnique Canadienne as well. Those crazy French!Barrieres Canadienne