The grand Metro plan for capturing fare evaders on buses -- the plan where drivers lock the rear door so passengers have to exit through the front -- has been unofficially abandoned by many drivers and erractically enforced by others.

"I would say about half the drivers" insist on the so-called zone check or fare receipts and "about half don't," said passenger Tom Edmondson as he boarded a Virginia-bound bus on Independence Avenue.

In fact, a check of major bus stops and transfer points throughout the metropolitan area during rush hours found very few drivers even pretending to use zone checks any more. The system -- designed to capture what Metro was estimating as "hundreds of thousands of dollars" in lost bus revenues -- simply became too much of a hassle.

"I don't run (the zone check system) because it takes too long," said driver Eugene W. Johnson Wednesday night after depositing a load of Virginians in their Kings Park West neighborhood. "I know where these people are going and where they get off. I told a lady tonight she didn't put enough money in there, and she added some."

That was the whole point of the system which started Oct. 1 -- to reduce the practice of paying a short-distance fare for a long-distance trip.Bus trips within the District of Columbia were not affected by the change. However, trips entering of leaving the District and crossing one or more suburban zones were.

The theory was that a passenger would board the bus, pay the fare to the zone of his destination, and receive a specially punched receipt from the driver. When the bush arrived at the destination, the passanger would exit through the front door, the driver would examine the receipt and let him leave if it all added up.

The problem -- especially for passengers at the rear on a standing-room-only rush hous bus -- is that it takes a long time to fight to the front door. Irate passengers complained to their drivers and Metro has received a number of uncomplimentary letters.

In the absence of direction from management, drivers seem to have solved problems their way.

For example, a woman boarding a bus for Oxon Hill at the Federal Center subway sation Wednesday night said, "Our driver did it for one day, and there was chaos. Then he said, 'Listen, I know where you people are getting off, forget it.'"

But has Metro, which is running bus deficit this fiscal year of about $94 million (plus a rail deficit of about $34 million), realized an increase in fare collections?

The answer is, maybe. Metro's transit services division -- which runs the buses -- surveyed four bus garages on three days before the zone check, system began, then did the same thing two weeks after the system began. They discovered about a 5 percent increase in collected revenue.

Bus ridership may have increased to account for part of the revenue increase. However, no one knows because bus riders are not counted on a daily basis, but instead are estimated on the basis of quarterly surveys. Since rail ridership increased some in October, some of that increase doubtless trasferred to buses.

The biggest percentage increase of the division surveyed occurred in the Arlington garages. In October, the Arlington garages began providing new regular route service to Reston, however and the increase could be new riders. r

Six years after the Metro's public takeover of four private bus companies, the system has yet to developed reliable ridership and revenue data for specific bus trips.

Thomas S. Trimmer, Metro's bus superintendent, met yesterday with the 10 drivers who designed the zone check system.

"They recognize that some of the operators are not doing it and they're not happy aboput it," Trimmer said. "Unfortunately, the committee represents a very small part of the driver corps." Changes in the system, Trimmer said, will have to be devised and recommended to the Metro board.

Driver W. A. Hines, who has abandoned the zone check system on his Alexandria-Pentagon trip, put it another way. "There's no question some people try to cheat," he said. "I try not to make 'em feel quilty (when I catch them). You just have to know your clientele."