The atmosphere was reminiscent of a jovial bachelor party when a group of correspondent truckers sat down to a pre-arranged roast beef dinner Wednesday night at 7:30 in the Twin Bridgas Marrio T. By the time the dinner was over at 10:30 p.m., it had taken on the air of a military strategy session, with the truckers plotting to choke off traffic on the 14th Street Bridge in the midst of the morning rush hour.

At 7:55 yesterday morning, the well-laid plans of the previous night went into effect. Thirteen trailer trucks rooled onto the 14th Street Bridge in Virginia - stopped five lanes abreast when they got to the District of Columbia side, blocking rush hour traffic from moving. In minutes, the police arrived.

"Hey, is this the way to Washington?" Lonnie Krotz, a trucker from Illinois called to a policeman, admittedly to irk him.

Behind Krotz, traffic was sttoped for about eight miles on 1.95 and cars were backing up on the George Washington Parkway from as far back as National Airport.

By that time another group of 20 trucks blocked traffic near the Virginia entrance to the bridge. Metro bus drivers began letting passangers off in the riddle of the bridge and some angry, impatient motorists left their cars behind and walked across the bridge. The truckers hand them flyers that told of their support for the plight of farmers and of their problems as independent drivers competing with large trucking firms.

"We told them (the truckers) they had a choice - either move or be arrested," said Capt. Wayne A. Layfield of the D.C. traffic enforcement division.

The truckers eventually moved out, driving only 5 to 10 miles per hour as they inched toward the mall - but not before they had held up hundreds of commuters for as long as 40 minutes - all to point they said they felt Washington officials have been ignoring.

Thus the independent truckers became the second group of angry Americans in as many days to bring their cause directly to Washington officials, while at the same time expressing their frustration in a way that affects the people who live and work in Washington as directly as it does the officials.

During the morning rush hour Wednesday, farmers protesting low farm prices drove tractors along Interstate 66 in Fairfax County and then knocked two police cars off the road.

Spokesmen for the truckers go out of business, we go out of business," said Bob Green, an organizer of yesterday's protest and a reporter for Overdrive, the trade publication of the Independent Truckers Association. Independent truckers haul about 98 per cent of the fresh produce that is transported by truck across the country, Green said.

The truckers said they also were seeking to draw attention to a Congressional hill that they say would help them compete with large trucking companies by permitting them to transport a wider variety of products without first obtaining Interstate Commerce Commission permits. In return for coming to Washington and plastering "We support the Agriculture Strike" stickers on their trailers, the truckers to looby in Washington for the trucker's cause as much as for their own.

The truckers mingled with the farmers at the Agriculture Movement's rally at the Capitol yesterday afternoon, some urging the farmers to become more militant.

"We didn't tell them to get violent, we told them to take positive action," said Bill Scheffer, national vice president of the Independent Truckers Association. "But we told them they're going to have to do more than sit around talking to Congressmen . . . they've got to get on those tractors and park in the middle of the road . . . that's what it takes to get attention."

In 1974, the independent truckers staged a 10-days nationwide strike that forced closing at some steel plants and slaughterhouses across the nation. It was marked by violence - the stoning of trucks and the beating of trucks drivers.

In that strike, the truckers were protesting the high price of fuel and 55 m.p.h. speed limits imposed to reduce consumption of fuel because of the fuel shortage.

This time, the truckers said they want Congress to pass a bill that would enable them to transport regulated commodities without first obtaining an ICC permit. At present, fresh produce is the only commodity truckers can haul without the necessary permit. To transport processed materials, they must contract with a trucking company that holds ICC permits. In return for "lending" a permit, the trucking company skims off about 25 per cent of the fee to the trucker, according to truckers.