Good Friday brought New York another day of light traffic and relatively easy commuting despite the 4-day-old mass transit strike, but city officials warned that Monday is likely to be a nightmare.

With no religious holidays to keep people at home next week, the improvised transportation methods that stood up reasonably well this week could collapse into enormous traffic jams. In addition, public schools resume after spring vacation on Wednesday.

The strike looked no closer to a solution today than when leaders of the 33,600-member Transport Workers Union called it early Tuesday morning.

Metropolitan Transportation Authority Chairman Richard Ravitch said union leader John Lawe "was very pessimistic and said he thought it would be a very long strike" during a one-hour negotiating session that made no progress this morning.

"Therefore, it is obviously not a happy moment," Ravitch said.

The union wants Ravitch to drop his demand that workers increase their productivity in exchange for a pay raise, Ravitch said. "As long as the union says that productivity is nonnegotiable, we will not discuss money," he said.

Mayor Edward Koch continued his cheerleader role, urging New Yorkers to keep their spirits up, but he and the city's chief mediator, Walter Gellhorn, both took recognition of the difficulty of the present impasse by suggesting that prayers would be useful aids to the negotiations.

In a curious development, state Supreme Court Judge John Monteleone, who issued an injunction against the strike and is holding hearings to determine whether the union should be held in contempt because it ignored the injunction, invited Ravitch, Lawe and the three mediators to meet in his chambers.

The mediators declined to attend the session, during which, according to Lawe, the judge offered some fatherly advice.

A contempt finding by Monteleone would open the way for the strikers to be assessed penalties of two days' pay for each day they strike under a state law that forbids strikes by public employes.

"The penalties of the law are there -- we can't ignore them . . . it crucifies our people," union leader Lawe said.

He said he would work hard to obtain amnesty from the penalties. Only the state legislature can grant amnesty.

Koch said that there have been two recent strikes by public employes and after each the strikers have paid the stipulated penalties.

The law would also cost the union treasury about $100,000 a week in dues paid by the management.

Union leaders can also be jailed under the law, but Ravitch and Koch, while asking for the dollar penalties to be invoked, have said they hope Lawe will remain free so he can continue to negotiate.

A number of the city's largest employers said they may honor Koch's request that they go on a four-day work week during the strike. Metropolitan Life, Citibank, the Bowery Savings Bank, Brooklyn Union Gas, New York Telephone and Consolidated Edison, among others, said they may put at least some of their employes on four 10-hour day weeks.

Ravitch and Lawe agreed to another bargaining session with the mediators Saturday morning.