Major delays and cancellations persisted Tuesday at European airports including London's Heathrow, and on the Eurostar train link, leaving thousands stranded across Europe. Predicted snowfall at Heathrow did not materialize overnight, allowing cleanup crews to intensify their work, but more than half the flights at Europe's busiest international hub were expected to be canceled. Travelers were told not to come to the airport unless they checked with their airline to confirm their flight was operating. Major delays were projected. Eurostar, which links England to France and Belgium by train, also advised passengers to cancel their trips in the coming days and receive a full refund unless travel was absolutely necessary. There were problems in Germany as well. Fresh snowfall forced Frankfurt airport, Germany's biggest, to suspend takeoffs and landings for a few hours early Tuesday. Airport authorities said flights were suspended a little after 5 a.m. (0400 GMT). The first runway was reopened for business at about 8:30 a.m. (0730 GMT) and officials were working to clear the rest. Some 300 flights were canceled, the Associated Press reported.