Dear Dr. Gridlock:

Read your thoughts on how the Rosslyn tunnel will get very crowded once the Silver Line starts. Here is a cheap alternative that solves the problem:

Keep the Orange Line the way it is going from Vienna to New Carrollton. Let the Silver Line go from Reston to Largo, thus replacing the Blue Line’s route from Stadium-Armory to Largo Town Center.

Shorten the Blue Line from Springfield to Rosslyn, which then eliminates the Blue Line from going on the same track used by Silver/Orange lines.

Saves money and effort. And the folks going from Springfield will have an easy connection in Rosslyn. It’s not perfect for them, but a transfer should add only three to five minutes to their journey and save all three lines a ton of time waiting for clearance through the Rosslyn tunnel.

— Sal Johnson, Leesburg

Actually, the Metro staff is going with part of the plan that Johnson recommends. But Blue Line riders won’t feel any better about the complicated strategy for adding Silver Line trains announced last week.

The planners did decide to send the Silver Line through to Largo, rather than end its run at Stadium-Armory. Once the new line starts following that route, which could happen at the end of 2013, there won’t be any more Orange Line trains going to Largo.

Metro decided it would be unsafe and impractical to turn back trains on the aerial pocket track above the east side of the Anacostia River. It’s a tight fit. Positioning trains onto the pocket track could back up the eastbound Orange, Blue and Silver lines. And that’s assuming the delicate maneuver worked right every time. If it didn’t, the impact on rush hour would be horrendous.

More rail cars will be needed, but the level of service to Largo will remain as it is today, transit officials said. Still, this issue on the east side of the new line is relatively simple compared with the planning to make the west side work.

The key problem that Johnson and I are discussing begins at the Rosslyn tunnel, where the Blue and Orange lines meet. Metro can’t put through any more than 26 trains per hour on the route through downtown D.C.

When the Silver Line begins operations between Wiehle Avenue in Reston and Largo Town Center, its trains will go through the tunnel at a rush-hour rate of one every six minutes.

That’s a lot of extra trains. The math works only by reducing the number of Orange Line trains going through while further cutting back on the Blue Line service.

I say “further” because some Blue Line riders lost trains this summer when Metro revamped rush-hour service and created the “Rush Plus” configuration. Done partly in anticipation of the Silver Line, Rush Plus added trains on the Orange and Yellow lines while cutting back on the Blue Line.

During rush hours today, Blue Line trains are scheduled to arrive at platforms six minutes apart, and there’s a gap of about 12 minutes until the next one.

Many Blue Line riders were really unhappy about that. Under the new plan for Silver Line service, they will be even less happy, because they will lose more service.

Metro officials said they analyzed several service plans. One was to have trains operate every seven minutes on all the lines involved, but that wouldn’t match the ridership demand the transit authority sees evolving.

Transit officials have said they can’t turn back the inbound Blue Line trains at Rosslyn under rush-hour conditions, a key element in Johnson’s plan. There’s no track configuration that would allow for that.

So under the new plan, the Blue Line trains will reach platforms every 12 minutes, whether or not it’s rush hour.

At least, it’s easier to remember.

Dr. Gridlock also appears Thursday in Local Living. Comments and questions are welcome and may be used in a column, along with the writer’s name and home community. Write Dr. Gridlock at The Washington Post, 1150 15th St. NW, Washington, D.C. 20071 or e-mail