Striking members of the International Brotherhood of Teamsters continued to picket 13 Consolidated Rail Corp. intermodal terminals Tuesday as the railroad began the cumbersome legal process that could take until the end of the week to re- move all pickets from its gates.

Picket lines came down at North Kearny, N.J., and Worcester, Mass., after employees signed contracts with the new operators of those terminals.Claiming it is the victim of an illegal secondary boycott, Conrail - a major operator in the Midwest and Northeast - filed unfair labor practice charges Monday at the Philadelphia regional office of the National Labor Relations Board.

The strikers were employees of PTL Transportation Services Inc. of Conshohocken, Pa., which operated the terminals for Conrail under contract.

The Teamsters acted to protest Conrail's plans to hire new contractors at its intermodal facilities. While employees at the terminals are covered by the Teamsters' National Master Freight Agreement, new contractors would be free to treat all employees as new hires, with substantially lower pay and benefits.

By putting pickets at the intermodal terminals, the Teamsters effectively hit Conrail as well as their employer. Because they are not railroad employees, Conrail contends the Teamsters fall under the jurisdiction of the Taft-Hartley Act, which forbids secondary boycotts. Secondary boycotts are legal under the Railway Labor Act.

Under Taft-Hartley Act procedures, the general counsel of the National Labor Relations Board must make a determination that an unfair labor practice is occurring. Once he does, he can seek injunctive relief from a federal court.

One source, who asked that he not be identified, said it probably would be at least 72 hours before a restraining order against the Teamsters would be sought.

Meanwhile, most Conrail operations appeared to be returning to normal, although the railroad refused to discuss steps it was taking.

Bob Kenney, a spokesman at United Parcel Service headquarters in Atlanta, said, "We're doing better today than yesterday, and are just about back to normal."

Another source, who asked not to be identified, said UPS, whose drivers also are members of the Teamsters, had managed to make a separate arrangement with the Teamsters so that its trailers could enter and leave the struck terminals. Neither Conrail nor UPS would confirm that report.

U.S. Postal Service bulk mail was returned to Conrail as of 2 p.m. Tuesday. The USPS had admonished Gordon Kuhn, senior vice president of marketing for Conrail, to do everything in his power to restore service to contract levels.

Service problems appeared most severe at Columbus and Cleveland, Ohio, while pickets at Columbus, Indianapolis and East St. Louis, Ill., still were keeping union train crews from reporting to work.

Columbus remained a hot spot Tuesday as police stood guard as angry Teamsters from Local 413 queued up to block United Parcel Service trucks from entering Conrail's intermodal terminal there. "If any of our trucks are crossing picket lines, they're not driven by union drivers," said a UPS official in Columbus.

Conrail would not discuss how it was coping, but confirmed that supervisory personnel were operating some trains and that others were being rerouted to avoid entering areas where pickets were present.

Sources said the railroad generally was handling so-called hot cars, but that other business on the western end of the rail system was affected.