Most of Amtrak's railroad police from Washington to Boston refused to work yesterday in a union dispute over the arrest powers of the 362-member police force, and the police union picketed New York's Penn Station and other sites -- including Union Station here -- in an effort to shut down the system.

Amtrak obtained a court order at 10 o'clock last night from U.S. District Judge Stanley S. Harris prohibiting picketing or disrupting operations. Harris scheduled a hearing at 10 a.m. today on Amtrak's request for an order banning the sickout by protesting police throughout the Northeast corridor.

Police pickets at both Penn Station and Union Station dispersed late last night after they were notified of the court order, and Amtrak spokeswoman Sue Martin said shortly before midnight that no disruptions of service were expected overnight. "We do not anticipate any further problems right now," she said.

Amtrak said in court papers that if the police strike and picket, "such actions would halt all train service whenever they took place." Other rail unions, including the train engineers, would be expected to honor the picket lines and possibly shut the Amtrak system, according to union and company sources.

Amtrak officials said last night there was no disruption in service of its 110 daily trains, but added that if the walkout succeeds it could cost the system up to $700,000 a day.

Management personnel were used to replace the members of the American Federation of Railroad Police, who either called in sick Tuesday night or claimed illness yesterday and went home. On yesterday's work shifts, Amtrak told the court the numbers of police absent included 26 out of 31 in Washington, 56 of 68 in New York, and 20 of 28 in Philadelphia.

The dispute was sparked by two arrests made over the weekend by police employed by New Jersey Transit Inc., a commuter railroad that uses Amtrak-owned tracks within that state. The walkout follows a long-running dispute between the company and the union, which has been working without a contract for nearly a year.

The American Federation of Railroad Police said the arrests performed by the New Jersey officers were a violation of the labor contract, which gives the union "exclusive police functions" over all Amtrak property, including trains, tracks and stations owned by Amtrak, said union lawyer Erick F. Larsen.

New Jersey Transit police also processed the arrests, a duty normally assigned to Amtrak police, Larsen said.

Amtrak spokesman Clifford Black said the rail arrests involve "quite a bit of paper work, which permits the filing of overtime claims" by police, "and it is quite conceivable that they want to be in a position to take advantage of that overtime."

Larsen said the Amtrak police believe the company is trying to "bust the union" for financial reasons, but also because union officials testified last year before a House subcommittee on government and transportation, and "they told Congress that Amtrak labor relations is a kangaroo zoo" of poor management.