Metro subway commuters may get in and out of the New Carrolton station parking lots a little more quickly if the trouble-prone toll gates are replaced by a team of toll collectors, as a special Metro task force has recommended.

But easing parking-lot problems will not automatically end the traffic jams outside the New Carrolton station, where home-bound commuters, once they manage to get through the troublesome gates, often must wait an additional 10 to 20 minutes on overloaded county and state roads before they can get into free-flowing traffic.

State plans to improve the Rte. 50 access to Garden City Drive -- which serves several new office buildings and the New Carrolton Metro station -- have been approved, but because of the shortage of state highway funds, county officials say it may be five or six years before the multi-million dollar interchange is built.

The delays and traffic jams have caused some commuters to give up on the on the subway and go back to driving their cars to work.

A switch to toll collectors is expected to expedite the flow of traffic in Metro lots, according to Metro spokesman Cody Pfanstiehl. By 1990, Metro will be operating the "the world's largest parking-lot system," Pfanstiehl said.

New Carrolton, the largest and most congested of Metro's nine subway parking lots, with 2,660 parking spaces, has been a battleground between Metro and motorists since it opened in 1978.Its automatic coin collectors malfunctioned from the start, causing frustrated commuters to break or remove hundreds of the wooden gates. Motorists still break or unbolt the gates, and sometimes remove several gates in a week, commuters and attendants say.

Metro now hires "monitors" to man the gates during evening rush hours. These helpers, many of whom are college students, stand over the coin machines with screw drivers to keep them going. Still, the gates get broken at night after the monitors have left, when commuters throw handfuls of change into the machines, causing them to jam.

"I've had to wait 30 minutes to get to Route 50. And sometimes you can't get out of the lot at all. It's madness. That's when tempers flare and people break gates," said James Fasone, a Veterans Administration employe who lives in Bowie.

While most commuters interviewed at New Carrollton last week complained about the traffic jam on Garden City Drive -- the responsibility of the state and county -- one Kettering resident, Kenneth Vilsack, said parking and commuting by Metro had become so expensive and so slow that he planned to commute to Washington by motorcycle in the future.

"It costs $1.55 each way (on Metro) and $1 to park, and then there's the hassle with the gates. I say the hell with it. I'm going to ride my motorcycle."

"This whole place is a mess," said Bernice Fairman of Greenbelt, who works near 12th Street and Pennsylvania Avenue NW. "I've been riding Metro since it opened, and I like it otherwise. But that road! I've sat here 20 minutes" waiting to get out of the parking lot and onto Route 50.

Metro's all-day parking spaces, which currently number 5,600 earn the transit system $1.6 million a year. Parking space will be increased approximately tenfold by 1990 and will bring in about $20 million a year, Pfanstiehl estimated.

An extra 10,000 parking spaces -- for a total of 65,000 -- could result from designing more spaces for compact cars, the task force reported. More than 60 percent of the cars now parked in Metro lots are compacts, a Metro survey found last fall.

Fulltime attendants at Metro lots would help improve parking-lot security and prevent most vandalism to cars, the Metro task force report concluded. It noted, however, that parking meters should continue to be used at small Metro lots and for short-term parking.

The Metro board, whose budget committee enthusiastically received the parking report last week, is expected to approve the shift to cashier operations. It remains to be decided, however, whether Metro should operate the lots itself or contract with an outside firm. It could be some time before a cashier system actually goes into operation, Metro officials said.

The task force recommended that permit parking, begun at New Carrolton in 1979, be expanded to all subway stations. It yields the most revenue for Metro, since the reserved parking spaces cost more and are rented on a monthly basis.

Among the drawbacks to a metered parking system, the report cited the costs of maintenance and repairs, and of hiring attendants to check the meters and issue tickets to violators. The fines from parking tickets -- now totaling between $100,000 and $200,000 a year -- go to local jurisdiction, not Metro, which is another reason a meter system offers Metro less revenue than a cashier system, the report noted.

The cost of operating parking meters in a 500-space lot is $178 a year, the report estimated, compared with $175 for automatic gates, $142 for a contract cashier system and $122 for a Metro-operated cashier system.

Most of Metro's present and future parking lots, and most of the large lots, are in suburban Maryland. After New Carrolton, the largest lot now in operation is Landover, with 1,124 all-day spaces, followed by Cheverly with 499, Addison Road with 482 and Capitol Heights with 321. Silver Spring has 48 short-term spaces and Takoma 82, which are not included in the totals. CAPTION: Picture 1, Metro parking attendant Don DeWeese, of Greenbelt, monitors toll gates at the New Carrollton station lot to make sure commuter traffic flows smoothly at rush hour.; Picture 2, Local traffic and commuters leaving the New Carrollton station parking lots create a bumper-to-bumper jam at rush hour.; Picture 3, Subway commuter Kenneth Vilsack, of Kettering, is fed up with congestion at Metro parking lots.PHOTOS BY DENNIS WHITEHEAD FOR THE WASHINGTON POST