Montgomery County asked the Interstate Commerce Commission this week to turn over 84 acres of railroad right-of-way property to the county government for a hiking trail and cross-county transit line.

The action is the latest development in a long-running debate over what to do with the land along the Chessie Railroad's Georgetown branch line, which runs for 10.7 miles from Silver Spring to the Georgetown waterfront in the District of Columbia.

CSX Corp., Chessie's parent company, has asked the ICC, which regulates railroads, for permission to abandon the line because it is no longer profitable. The rail branch was used to deliver coal to a General Services Administration plant in Georgetown that supplies heat to 120 federal buildings.

Reports last year that the railroad company was considering selling much of the line's right of way to real estate developers touched off protests from the National Park Service, government officials in the District and Montgomery County, environmental groups and owners of homes near the railroad. The branch line passes through the C&O Canal National Historic Park and upper-income residential sections of Montgomery and Northwest Washington.

CSX has placed a net value, after fees and charges associated with sales transactions, of $19.5 million on the entire 123.1 acres it owns along the Georgetown branch line, according to CSX spokesman Thomas E. Hoppin. The corporation has agreed to attempt an exchange of the nearly 40 acres in the C&O Canal park for other federal property of equal worth, according to CSX and federal officials.

In their statement to the ICC, Montgomery officials asked the commission to disapprove abandonment of the property, and instead to invoke a section of the National Trails Act to permit county use of land within Montgomery "until we are able to buy it" from CSX, according to Glenn S. Orlin of the county planning and project development office. If abandonment is approved, CSX would be free to sell the property to anyone it wishes, he said.

The Trails Act allows a local government agency or private organization to operate public hiking and biking trails on unused railroad land that a company no longer uses but has not abandoned. Montgomery is proposing to use the right of way from the District boundary to Bethesda for a trail, and the remainder of the property from Bethesda to Silver Spring as both a trail and for cross-county public transportation. The county will study the possible uses of a light rail line, trolleys or buses, Orlin said.

If the ICC does not approve the plan, Montgomery County will ask the commission to prohibit CSX from disposing of the property for 180 days so that county officials will have time to negotiate a purchase, he said.

Hoppin disputed county officials' interpretation of the law, saying the company could not sell the property until it has a certificate of abandonment from the ICC.

"We have no intention to commercially develop the property," Hoppin said, but will hold on to the property until the federal and local governments or environmental organizations can arrange for converting the property to public use.

But whether the land is turned over to a local government or private organization under the Trails Act or is sold outright, "We're going to be paid for the property," the CSX official said.

Environmental organizations contend the legislation states that, when land is assigned for trail use, the railroad retains ownership and the organization operating the trail pays management costs and assumes liability for the property. The management organization does not have to buy the property, they said.

An ICC official said, however, that the railroad company can require a management firm to buy the land if the rail company wishes or can allow its use without charge.

Another ICC regulation implementing the Trails Act allows railroad companies to decide whether unused rights of way will be used as a trail or disposed of in some other way. This interpretation has been challenged in two lawsuits, one filed in the District by the Rails to Trails Conservancy, a consortium of environmental organizations, and another brought by the State of Washington, according to David Burwell, executive director of the conservancy.

The 1983 amendments to the Trails Act "clearly state that, if a qualified land-management entity meets certain criteria and if it requests the conversion of an unused rail corridor to trail use," the ICC must approve such use, according to a conservancy statement.

Before the ICC makes a decision on the CSX abandonment request, it must draft an environmental impact statement. Experts next month will begin studying the history and architectural importance of the railroad right of way.

The ICC has "substantial data" showing "a wealth of architectural resources" on the railroad property from as long ago as 6,000 years, said Carl Bausch, head of the energy and environmental section in the agency's transportation office.

Remains of prehistoric Indian camps and fishing villages, a mid-19th-century commercial and industrial community and an old foundry are among the treasures buried on several portions of the railroad land, according to Catherine Slusser, an archaeologist with the D.C. Office of Historic Preservation.

Railroad bridges and the Georgetown branch line itself, or parts of it, could become eligible for listing on the National Register of Historic Places, said Robert Maestro, project coordinator for the environmental study. The bridges, rails and ties are included in the study because the Chessie's abandonment request includes a proposal to remove them. Hoppin said CSX's purpose is to avoid injury to horse riders, hikers or pedestrians and that the company would lose money on the material it salvages.

The impact on District residents and traffic if coal is delivered by truck through the city to the Georgetown heating plant also will be investigated, Maestro said. For the past several months, coal has been trucked from Bladensburg via New York Avenue and K Street.

Negotiations between CSX and federal officials for an exchange of government property elsewhere for the railroad land along the C&O Canal in the District continued this week in a meeting that included GSA officials, according to P. Daniel Smith, Interior Department deputy assistant secretary for fish, wildlife and parks. The GSA controls federal property of several types, including "surplus" buildings, "giving us more things to choose from" for the exchange.

A swap involving federal property will require congressional approval, which could not be sought until next year, Smith said.