Today is another landmark in the history of shifting Metro rapid transit scheduling, and as could be expected, Metro's switchboard was jammed yesterday with calls from anxious riders trying to find out what the latest changes mean to them.

A caller wondered how he could get by subway from McLean to the Smithsonian now that his bus was rerouted; another had heard, erroneously, that all bus runs in Northwest were going to be terminated. Some Virginians demanded to know why they had to pay more now than residents of the District of Columbia and Maryland and other people vowed that they would never ride the subway because it travels under a river, or because the escalators go too fast.

"Some people are nice about it, and some of them are nasty; but basically the changes are too confusing for a lot of them," said the beleagured supervisor of Metro's phone information room, Linda Goetchius.

She and the 24 operators at the information center were kept scrambling yesterday because beginning this morning, Metro will change or climinate 210 bus routes in an attempt to economize by feeding more commuters into the subway system.

For many people that means learning where to get on buses and off at subways stops, and vice versa, and how much it will all cost. Metro officials have distributed flyers in buses over the last month explaining the changes on that particular route, but they expressed no surprise that people were calling in, anyway.

"Whenever something is happening to change people's lives they look for assurance," said Metro's marketing director, John Warrington. "We expect Monday to be one of the busiest days (for information requests) in our history.

Some of the senior citizen callers yesterday complained that they were too old to remember all that Metro now demanded. "You can explain to some of them three times what they have to do and when you're finished they'll say, wait a minute, let me get a pencil," said Goetchius.

While operators pored through a two-foot thick compendium of route and fare schedules some callers broke into profanity. "What in the hell does Metro expect us to do?" said one. "The rails aren't working right - how do I know I can get to work on time?"

"Some of them want us to take them by the hand," said Goetchius, "we can't guarantee that the trains won't have problems."

The changeover was supposed to go into effect two weeks ago, but was delayed because of mechanical difficulties in the newly opened Blue Line, which runs from the Robert F. Kennedy Stadium area to National Airport.

Not all the callers were abrupt yesterday. Many were patient and some said they looked forward to riding the subway because it would be faster and more convenient, some operators reported. But some people complained about having to spend more money to do so.

Riders transferring from the bus to the train will have to pay two fares now. Train riders transferring to a bus in the District and Maryland however, will get a free bus ride after they leave the train. Riders who transfer from the train to Virginia-bound buses will have to pay bus zone charges in addition to their subway fare.

For some commuters transit costs will go up 30 or 40 cents; for others the cost will remain the same, or even drop slightly.

The new routes and fares are sufficiently confusing that even the information operators conferred among themselves and their supervisor before answering some of the questions.

"How much will it cost me now to get to the Smithsonian and how do I do it?" the McLean caller asked, sending the information operators into a conference. They decided that the caller had to take a No. 5 bus to Farragut Square and then catch a subway to the Smithsonian.

His bus fare from zone 2 - which includes the McLean area - is $1.10 and the subway fare is 40 cents. Previously the man had to pay only the bus fare because he transferred from a No. 5 bus to a No. 52, which went to the Smithsonian. That bus still goes there, but it is now a long walk from the No. 5 bus to transfer to the No. 52.

In the evening, this commuter pays 40 cents for the subway, and then gets a 50-cent credit for transfer to a bus back to Zone 2. That means he pays 60 cents for a bus ride that had cost him $1.10. The total cost increase for this man, the operators decided, was 30 cents.

If this sounds more like algebra than a transportation shcdule, it is because "it is very confusing," said supervisor Goetchius.

Generally, here is the plan:

Bus routes that cross Key Bridge will be terminated at the Federal Triangle Metro station.

Bus routes that cross the East Capitol Street Bridge will be terminated at the Stadium-Armory Metro Station.

Bus routes that cross the Sousa Bridge (Pennsylvania Avenue Southeast) will be terminated at the Potomac Avenue Metro Station.

Bus routes that use the Rhode Island Avenue or New York Avenue corridors will be terminated at the Rhode Avenue Metro Station.

Some other bus routes will be terminated at Federal Center SW, Farragut West. Union Station and the Pentagon Metro stations.

Bus routes that cross Roosevelt Bridge will be terminated at the Federal Triangle Metro station.

"One woman told me that no one over 30 would ride the subway because it goes too fast," said one operator, Celia Walker. "I felt like telling her that I'm 42 and I ride the subway all the time, but I didn't."

Some of the operators, to relieve tension, jog to the restroom, or pull at their hair.

Things may be worse for them the first week in September, Goetchius said, because more buses are scheduled to be rerouted then and other riders will be calling because schools are opening. "I should have asked for vacation then," she said, "but two other supervisors already beat me to it."