Metro officials are eyeing a Brown Line to join the system's existing palette.

The transit agency is planning for the future, looking at creating a train line that dips from Friendship Heights into the District and back up to Silver Spring and past White Oak. It's also studying a line along the Capital Beltway loop, diverting the Blue Line from its current route across downtown to create a midcity rail line, or running an offshoot from the Green Line to National Harbor.

None of the plans is funded or even firm. Engineering hasn't been done and land hasn't been set aside. But the transit agency is studying what it will need by 2040 to accommodate growth in the region and relieve pressure on the system.

Officials plan to discuss some possibilities with regional leaders Wednesday, then hold workshops in July to hear riders' thoughts. By next spring, Metro hopes to have a final plan identifying which projects it will consider developing.

Metro in 2040?
The agency is studying new rail lines:
» Beltway Line: A loop around the Capital Beltway connecting existing Metro stations. Weekday ridership: 115,000 trips
» Brown Line: The Red Line offshoot would run from Friendship Heights down to Foggy Bottom and Union Station, then bend north to Georgia Avenue-Petworth, diverging from the existing Red Line to reach White Oak and Cherry Hill Road. Weekday ridership: 101,900 trips
» Midcity line: A realigned Silver or Blue Line that runs along M Street, stopping in Georgetown, rejoining the Orange and Blue lines near the Anacostia River

"These projects take a long time," said Tom Harrington, Metro's director of long-range planning. "That's why we really feel like we've got to get started now."

Some of the ideas aren't new. A Beltway line was discussed two decades ago, Harrington said, but only the planned Purple Line gained traction. Also, the Brown Line has had a few iterations, including as a color to explain diverted Blue Line trains in 2008. Harrington called the color a placeholder.

Metro officials also are looking at some scenarios that wouldn't require new lines -- or would only incorporate the most cost-effective ideas. But he added, "We're testing some things we know are a real long shot."

Metro did a similar long-range plan in 1999. Some of the ideas came to fruition: the Blue Line was extended to Largo Town Center, the Red Line's New York Avenue fill-in station was built and the system runs longer trains to accommodate more riders.