People board a Metro train at Reagan National Airport in 2012. (Matt McClain for The Washington Post)

I have always wondered why there are three tracks at the Reagan National Airport Metro station. There is an outbound track and an inbound track shared by the Blue and Yellow lines. And there is a center track not being used or being used sparingly. What was WMATA’s plan for the center track?

Daniel S. Chan, Washington

Today is Learn About Choo-Choos Day here at Answer Man HQ. And the first thing on our agenda is “All About Pocket Tracks.”

That’s what you call the track between the two main tracks at National. A pocket track is used to take a train off the main line so it can reverse direction without disrupting service.

The track is switched, the operator directs the train onto the pocket track and comes to a stop.

“The length is just long enough to accommodate an eight-car train,” Metro spokesman Dan Stessel said. The operator can then shut down the train, walk through the cars to the other end, power up and come back in the opposite direction.

Chains span the gaps between cars in Metro’s 7000-series trains. (Marvin Joseph/The Washington Post)

There are seven pocket tracks in use in the Metro system. Two — at the airport and West Falls Church — are in the center of the platform islands. The others are just beyond the stations, near Stadium-Armory, Mount Vernon Square, Farragut North, Grosvenor-Strathmore and Silver Spring.

Most pocket tracks are near stations that were once at the end of the line. The pocket track at National is functioning that way right now. It’s the end of the Blue and Yellow lines while platform maintenance is underway.

Trains can be staged in pocket tracks, waiting to take up slack during rush hour. And they’re used for special events. During Nationals games, Green Line trains unload riders at Mount Vernon Square, go into the pocket track, then reverse direction and head back to Navy Yard-Ballpark.

The system will soon gain another pocket track, at Wiehle-Reston East on the Silver Line.

I have wondered why the recorded announcements on the newer Metrorail cars endlessly (and repetitively) tell us, stop after stop, that “this is a 7000 series train.” Could someone tell Metro that we don’t need to be reminded multiple times per trip that we are on some model train?

Grant P. Thompson, Washington

By the time you read this, you probably won’t hear that. The issue that demanded the seemingly obvious auditory reminder should have been rectified.

The short story is that the recorded message was just for riders who are blind or visually impaired, a way of warning them not to step into the gap between cars.

The longer story is this: All the previous series of Metro train cars work in pairs. An eight-car train is four sets of twins. There are chains between all of the cars. The chains can be detected by the wave of a cane and, hopefully, will catch a falling person and prevent him or her from reaching the tracks below.

The 7000-series trains, however, work in what are called four-packs: two sets of quadruplets. Originally, where the two four-packs were united — between cars four and five — was what’s called an intercar barrier. This barrier comprised rubber “wings” without chains. A blind person waving a cane might mistake the empty space for a door and step forward.

The original design was compliant with the Americans With Disabilities Act, Stessel said, but Metro agreed when the Federal Transit Administration asked for changes. Knowing it would take manufacturer Kawasaki some time to retrofit more than 600 cars, the announcements were rolled out.

The idea was that people with visual impairments would hear the announcements and know to tap to find the floor. (That is, if they knew what a 7000-series car was. There were complaints that visually impaired out-of-town visitors might not have a clue.)

The 7000-series cars have all been retrofitted, Stessel said, and the announcement began coming off individual cars in early June.

“We’ve been advised they should all be off,” Stessel said, “but there might be a car or two [that still has them], which we’ll get to.”

Questions, please

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