Boston — When all else fails, turn to Congress. That's the tack that independent trucking leaders are taking as they search for a face-saving way out of their declining week-and-a-half-old strike. And some members of Congress seem ready to help them find it:
* Various members of the House of Representatives have been meeting continuously with Independent Truckers Association (ITA) president Michael Parkhurst this week. They say they are working on a document - a ''kind of commitment by Congress to address the issues, to lay out the concerns of the truckers and what they think needs to be done,'' in the words of Rep. Peter Kostmayer (D) of Pennsylvania.
The ITA wants hearings on the matter.
* At least six bills have been introduced that would repeal or at least amend the heavy schedule of new federal tax increases that triggered the strike.
Some governors, notably Victor Atiyeh (R) of Oregon, have pledged to contact their congressional delegations on the strikers' behalf.
Meanwhile, members of the Massachusetts Independent Truckers Association staged the latest of a series of convoys by drivers around the country to dramatize their plight.
Their 40-mile drive to Government Center in Boston Wednesday was delayed a day because of snow and uncertain road conditions, and they missed meetings with Democratic US Sens. Edward M. Kennedy and Paul Tsongas of Massachusetts. They settled for audiences with aides to key congressmen, and vowed they would apply continued pressure in the hope of forcing action on their grievances.
There is mounting evidence, however, that the mass shutdown by independent owner-operators is not having its intended effect. Reports of increased truck traffic are coming from many states, and fresh produce apparently is finding its way in near-normal quantities to most markets - although at rising prices as nonstriking drivers demand double their usual pay.
There also are indications that the action is providing railroads with a modest windfall as they attempt to make up for lost time in competing for freight traffic.
Still, ITA spokesman Bill Martin estimates that at least 70,000 owner-operators continue their refusal to drive. ''We're not desperate at all,'' he claims. ''We've got a game plan, and we're following it.''
The strike, he says, ''has already attained its first goal: getting the attention of Congress.'' The next goal: ''to see what we can get from Congress [ in the way of] legislative reforms.''
But he adds, ''I'm not saying that's what we would settle for - repeal or nothing.''
Mr. Martin dismisses the offer Tuesday by US Transportation Secretary Elizabeth Hanford Dole to meet with ''all responsible representatives'' of the trucking industry to discuss the issues behind the shutdown.
Mrs. Dole called the strike a failure.
The ITA, Martin says, believes the Department of Transportation (DOT) has already brought leaders of lesser-known trucking groups that do not support the strike to Washington for such a meeting. Not only would the outcome be unfavorable to the ITA cause, he predicts, but the Reagan administration would then use it to back its argument that the strike is unjustified.
''They [DOT] don't want to deal with us because they know we mean business,'' he says. ''And they know these other people are spineless.''
The shutdown, various ITA sources indicate, will likely last at least another week.
Says Ed Jasie, a striking trucker from Westminster, Mass., however: ''This time next week, I'll be back to work. We've done all we can do.''
Mr. Jasie says he grossed $90,000 last year hauling electrical equipment, but netted only $27,000. Out of that amount, he says, he had to routinely set aside money to buy a new tractor by 1987. Reason: Trucking firms that lease the services of independent drivers draw the line on rigs more than five years old.
Inconvenience to the public because of the strike generally has been minimal. The Department of Agriculture reported rail deliveries of food up by as much as 50 percent in some major cities, notably Baltimore. This claim could not be substantiated by calls to major railroads, however - possibly because of fears that if it were admitted, acts of violence and sabotage might be directed at freight yards.
In fact, some rail-industry sources indicated security measures were being tightened in yards near major cities.
Only the Southern Pacific would acknowledge a significant increase in produce shipments since the start of the strike. Spokesman Al Bradshaw said vegetable and lettuce traffic is up ''25 to 30 percent'' from Texas and southern California since the start of the strike.
Seaboard claims its new 26-hour delivery service from Florida to Wilmington, Del., is ''very successful.'' But information officer Ray Bullard could not say how much of that is attributable to the truckers shutdown.
The Chessie System, Union Pacific, and Santa Fe all declined to comment or denied there was a measurable upturn in produce shipments. But a Chessie spokesman reported some increase in steel hauling.
Conrail spokesman Saul Resnick said only that his line exceeded traffic projections for January and the increase has ''continued in the midst of the truckers strike.''
But ''these reports of a bonanza for the railroads I do not think bear any resemblance to reality,'' Mr. Resnick added.
From a low of 9 percent of fresh-produce traffic hauled in 1979, the railroad industry has built its volume back up to 11.7 percent, according to Frank Wilner , spokesman for the Association of American Railroads.
''The strike,'' he says, ''gives us the opportunity to prove to the shipper that we can be as competitive as the motor carrier.''