French farmers angry over increased taxes and European agriculture policies they say threaten their livelihoods were on the roads well before dawn Wednesday, blocking highways and access roads to Paris. The protests, now about two weeks old, brought traffic to a standstill in many places as tractors blocked lanes or entire sections of highways for miles, and 18 people were arrested Wednesday.

The farmers remained determined to keep up pressure on France’s government to change its policies, and there was no sign of an imminent end to their blockades encircling the capital. They advanced Wednesday toward Orly airport, south of Paris, and other major cities and towns, including Lyon in the east and Toulouse in the southwest.