The year 2000 will be a groundbreaking one as transportation agencies throughout the Washington region plan work on dozens of road and transit projects, from huge highway interchanges in Fairfax, Prince George's and Montgomery counties to a new Metrorail station in Northwest Washington.

In Loudoun County, the Virginia Department of Transportation intends to add two lanes to Route 7 between Dranesville Road and Lakeland Drive and pave three miles of Woodburn Road, over the objections of some residents who want to see it remain a gravel byway.

The most expensive item in either Virginia or Maryland is a $19.6 million project in Fairfax to convert the intersection of Routes 28 and 29 near Centreville into an interchange. Scheduled to begin in the summer and continue through fall 2002, the construction is designed to keep pace with rapid growth in the western part of the county as well as in neighboring Loudoun and Prince William.

"This is a major bottleneck and headache for commuters during the morning and evening rush hours. By building a partial cloverleaf, we're going to be able to ease the congestion considerably," VDOT spokeswoman Joan Morris said.

Money for the construction was included in an initiative by Gov. James S. Gilmore III (R) to accelerate the receipt of federal funds promised for the state.

This spring, the department also plans to start widening three miles of Telegraph Road between Beulah Street and the Fairfax County Parkway and between the Franconia-Springfield Parkway and Route 1.

Among the first projects scheduled to begin this year in Virginia is work to improve the Prince William County interchange of Interstate 95 and Route 234 and widen Route 234. Other major jobs slated for Prince William are the replacement of I-95 bridges over Route 619, improvements to the Route 28 intersections at Linton Hall and Vint Hill roads, and rebuilding the intersection of Routes 29 and 234 to add left-turn lanes and to make safety changes.

Much of VDOT's attention over the coming year, of course, will be devoted to the ongoing reconstruction of the Springfield interchange, which began last spring. Replacing the interchange, at the junction of Interstates 95, 395 and 495, is the most ambitious, complicated and expensive road project in the Washington area.

A $40 million effort to complete the northern section of the Fairfax County Parkway also is continuing, with construction on the final, 1.4-mile segment between Baron Cameron Avenue and Sunset Hills Road expected to start early this year.

In Maryland, the heftiest price, $17.3 million, will be paid to rebuild and redeck four aging bridges along the Capital Beltway in the Silver Spring area between Colesville Road and Georgia Avenue. The work, scheduled to last two years, is expected to affect traffic severely, adding to some of the worst congestion on the Beltway.

Another big-ticket item in Montgomery County is construction of a new interchange on the eastern spur of Interstate 270 at the Rockledge Drive connector and an upgrade of the interstate's junction with Route 187. This effort, projected to begin this spring and to cost $15.4 million, is designed both to smooth traffic flow and to offer surrounding businesses better access.

The coming year will also see the state move ahead with the top transportation priority in Prince George's: a new Beltway interchange at Ritchie Marlboro Road. The project, costing $15.1 million, is expected to ease congestion at the Beltway interchanges with Routes 214 and 4, officials said.

"It is a project which will provide great benefits to an area surrounding the Capital Beltway, providing safety and traffic flow improvements, and it's also going to help stimulate the economic development of the area," said Suzanne Bond, spokeswoman for the State Highway Administration.

Maryland also is scheduled to begin repaving and making safety improvements on the Beltway between Branch Avenue and Darcy Road in Prince George's.

Metro, in the meantime, is planning a series of transit projects, most notably construction of a new $60 million rail station near the intersection of New York and Florida avenues in Washington, if funding becomes available this year.

The Red Line station, between the stops at Rhode Island Avenue and Union Station, would be part of the city's ongoing efforts to redevelop the New York Avenue area. Major property owners in the area have pledged to underwrite $25 million of the cost.

Also scheduled to start this year is the second phase of construction to expand the Metrorail station at Mount Vernon Square/University of the District of Columbia in preparation for the crowds expected to accompany the opening of the new Washington Convention Center. This work, scheduled to begin in February and to finish in spring 2002, involves enlarging the station's entrance and mezzanine.

Other new transit projects include building a pedestrian footbridge at the Prince George's Plaza Metrorail station, construction of canopies over station escalators now exposed to the weather and renovations to the bus garage at South Capitol and M streets SE.