The Chessie Systems Railroad has threatened to go ahead with residential and commercial development on more than 100 acres of land in the C&O Canal National Historic Park unless the National Park Service agrees to buy the property for $15 million, according to a park service official.

The land is railroad right-of-way along tracks that run through a portion of the park in the District. The park service wants to use the land for hiking and biking trails.

"We feel like victims of the great train robbery," said John Blair, of the park agency's capital region, describing a meeting of park and Chessie officials held last week. The national park agency, which does not have the $15 million to acquire the property, still hopes the railroad will decide to donate the land, Blair said.

Residents of neighborhoods along the rail line, which until recently was used to haul coal, oppose development, and D.C.'s comprehensive plan designates the property as open space. "I think the city is committed to keeping that area open space," said City Council member Polly Shackleton, adding that she supports efforts to block development.

Donation of the property is impossible, according to Robert H. Tucker, a vice president of CSX Corp., the railroad's parent company. "We are compelled" to get the market value price for the property, which could be in the "range" of $15 million, he said.

The rail line was used to deliver coal to a General Services Administration heating plant at 29th and K streets NW, which supplies heat to 120 federal buildings. A railroad official said the company wants to abandon the line because it no longer makes money. The coal is now transported by truck from Bladensburg to the Georgetown plant. The Chessie proposes to make the trucking arrangement permanent, according to government officials.

The portion of the railroad property within the city runs from 29th Street NW to the District boundary, and is about 30 feet wide until it reaches the Palisades area north of Georgetown, where it widens to 60 and 70 feet, according to Blair. It is in Palisades that the Chessie officials said they envision town-house and condominium structures cascading from Potomac Avenue down the hillside to Canal Road, he said.

According to Blair, Tucker and another Chessie officer attending the meeting with Blair and John Parsons, associate director of the park agency's National Capital Region, said the price would be lower than $15 million if the railroad retained the Palisades property, which it regards as the most valuable for development.

Tucker said the railroad's position at the meeting was not that cut and dried. The Chessie System "would like to work with the park service to get the property transferred to them," using one of "several mechanisms," Tucker said. "The park service could buy and pay for it, or it could be exchanged for other properties the park service owns."

Tucker said he did not have any specific park property in mind for a swap, but added, "it's a possibility." A local development group that has been involved in discussions with Chessie officials may buy the right-of-way land, then make the exchange with the park system, according to Tucker, who said he would not "like to name" the developers.

The only federally owned park property in Washington that is worth $15 million is the Mall, Blair said. Park officials could not discuss a swap "because we don't know who we're dealing with or what land they're interested in," Blair added.

If the railroad company does not donate the right-of-way property, the park service will try to invoke a 1983 amendment to the National Trails System Act to acquire the land, Blair said. The amendment gives "user groups," such as a state or county agency, authority to take over unused railroad land for use as public trails if they are willing to assume managerial, financial, legal and tax responsibilities.

Congressional framers of the legislation and conservation organizations believe that if a group could meet those conditions, the Interstate Commerce Commission, which regulates railroads, might not approve abandonment, which gives the railroad the right to use the land as it wishes. CSX officials replied that "they would use no less than eight, and probably no more than 10, law firms" to oppose park service efforts to acquire the property under the trails act, according to Blair. "Our position is we don't think they can" use the legislation to take the property, Tucker said. "I'm in real estate. . . . We have a law department that handles these matters," he added.

Montgomery County has told the ICC it wants an opportunity to acquire the portion of the line that runs through the county.