West Berlin — Striking West Berlin employees of the East German state railway (Reichsbahn) severed the city's supply rail link with West Germany to press demands for higher pay and free trade unions. The 3,500 strikers stopped all freight and mail trains on the 110-mile rail corridor through Communist East Germany to the West. They said they might stop passenger traffic, too, if their demands were not met. West Berlin authorities say essential supplies for the city's 2 million citizens and its industry are in no danger of running out for the moment. However, the city is studying contingency plans to transfer stranded freight traffic to trucks and barges if the strike continues.