Bus, train and airport officials offer the following advice for holiday travelers: Before the going gets tough, get going early.

Bigger-than-usual crowds and long lines can be expected for the next week and a half because of the holiday season surge in travel.

Officials recommend that customers make reservations well in advance and arrive at the station with plenty of time to spare to keep their nerves from getting jingle-jangled.

Amtrak forecasts that its ridership will be up 25 percent over typical rail traffic through Jan. 4, with a daily average of more than 12,000 people passing through Washington's Union Station.

National and Dulles International airports are expected to handle a combined volume approaching 100,000 people on peak days this Christmas season, up about one-third from normal weekday passenger totals.

Preliminary estimates are that holiday traffic on trains and planes here will be about the same as last year at this time, the spokesmen said.

No estimate was available for intercity bus traffic over the next several days, but officials of Greyhound-Trailways Bus Lines described their business yesterday as brisk.

Train passengers with tickets are advised to arrive at the station about 45 minutes before departure time, said Amtrak spokesman Howard Robertson.

He suggested that people without tickets show up at least one hour early "just to make sure they get well organized before the train moves," and that all riders carefully bundle packages so they are not lost or stolen.

Airport travelers are also urged to leave early because of traffic congestion near terminals. However, officials say the parking outlook is favorable.

David Hess, spokesman for the Metropolitan Washington Airports Authority, said both airports had adequate parking during Thanksgiving weekend, which is traditionally the heaviest travel period of the year.

Until Jan. 2, several parking lots at National will feature a 30-minute grace period for which there will be no charge to drop off or pick up passengers.

At Dulles, there is a 20-minute grace period year-round at all parking lots.

The airport authority is offering a special deal on its Washington Flyer bus service, which serves the two airports, the West Falls Church Metro station and some hotels in Washington and Maryland.

Families and friends dropping off or picking up a passenger at National or Dulles can arrange to ride the bus free round-trip if the airport passenger pays the regular fare.

Motorists are reminded to avoid Washington's Whitehurst Freeway, which is being renovated. Even hitchhikers might want to get moving early, because the long-range forecast calls for low temperatures in the teens by Christmas Day.