Germany, Italy, and other parts of Europe are bracing for a holiday weekend of traffic chaos, jams and foul tempers when Austrian environmentalists close key Alpine passes Friday to protest the growing numbers of trucks and vacationers thundering through their valleys.

Declaring themselves the "Alpine resistance," the protesters plan a 31-hour blockade of the six-lane Brenner highway, the key Austrian link between northern and southern Europe, and disruptive action on other main routes between Germany and Italy.The Brenner pass, to be blocked at Schonberg just south of Innsbruck, will have open-air parties, concerts, religious services and children's games Friday in place of the usual columns of vehicles.

Traffic on the route has risen 43 percent since 1990 and is expected to rise another 60 percent by 2010, provoking the protesters, with overwhelming local support, to show how fed up they are with hollow government promises to ease the congestion by promoting rail freight.

"Only once the wheels are brought to a standstill will the politicians start moving," said Fritz Gurgiser of Transitforum, which is organizing the blockade.

Austrian police said they were deploying every available resource to prevent trouble. The Austrian automobile association warned of "total chaos" and the "traffic jams of the year."

German truckers' associations complained of "state anarchy" in Austria and said they would go to court for compensation for their lost business.

The Brenner highway will be closed from Friday morning until Saturday afternoon. The Tauern highway, which also crosses the Alps, will be subjected to hourly disruptions near Salzburg.

In much of Roman Catholic Italy, Austria and southern Germany this is a holiday weekend, and thousands of German vacationers will be trying to return home from their Whitsun week in the south.

The protest organizers hope 10,000 people will take part in the protests. "We've been hearing for years that the traffic is to be transferred to the railway, but nothing has happened," Gurgiser said. "If people come out, perhaps things will change."

Only last month European Union economics ministers agreed to outlaw protests inhibiting the free movement of goods across the union. But the environmentalists have highlighted the EU's dilemma: the conflict between freedom of assembly, demonstration and speech on the one hand, and freedom of movement of people, services and goods on the other.

Trucks are barred from the Alpine routes on Sundays and holidays, but under pressure from the transport lobby Brussels is planning to ease the restrictions.

The Bavarian Nature Protection Federation said the protests were a cry of desperation. "The blockade is a desperate call for help from man and nature in the Alps. They are suffering from the noise and the fumes of the ever greater numbers of cars and trucks."