Dear Dr. Gridlock:

I was disappointed to read that the seats in the new Metro cars would all be blue. It seems to me a no-brainer that the color of the seats should match the color of the line — red for Red Line, yellow for Yellow Line, blue for Blue Line, and so on.

Randall Swanson, Alexandria

DG: Riders often suggest ways of making it easier for fellow riders to figure out where they are in the Metrorail system. For example, when Metro was upgrading the warning lights at the platform edges a few years ago, some travelers proposed that the lighting scheme align with the colors of the lines.

That one wouldn’t work — at least not easily — in the sections where lines share platforms. A variable color scheme for seats also poses a practical problem, but one that I think riders will appreciate.

One of the new Metro cars set to arrive in Washington next month is seen at the Kawasaki Rail Car plant in Lincoln, Neb. Teh cars will have signs inside showing upcoming stations and a blue interior color scheme. The unvarying palette contributes to the cars’ interchangeability so they can run on all lines. (Courtesy of Washington Metropolitan Area Transit Authority)

The new rail cars on order and scheduled to begin service in 2014 must be able to operate on all lines. There won’t be a fleet of cars reserved for the Silver Line or any other part of the rail system. The transit authority will be able to switch them from line to line as needed.

There is a limit on this interchangeability. The new cars are so different from the previous generations that they can’t be combined with them. Riders won’t be moving along platforms to locate the new cars on the train. Arriving cars will be all new or all old.

Their interior design should make it easier to double-check where it’s heading, thanks to a new style of sign on the cars’ sides that shows upcoming stations.

This might be particularly important after the Silver Line starts running next year. Riders between the Rosslyn and Stadium-Armory stations will find their choice of lines expanded to three — Blue, Orange and Silver — the most of anywhere in the Metrorail system.

Silver Line goals

Dear Dr. Gridlock:

Your column about the Silver Line prompted me to ask a question I’ve wondered about since construction began: Will its primary goal be to relieve road congestion along the Dulles Toll Road corridor, or will it be to provide travelers with a way to avoid the roads when going to and from Dulles International Airport?

I ask because the Silver Line, like the rest of the system, is being built with only two tracks. Thus, like the other lines, it will be difficult if not impossible to run express trains to the airport.

Given Metro’s estimates that a trip from downtown D.C. to the Wiehle Avenue station will take 41 minutes, one can estimate that a trip to the airport would require about an hour. Other forms of ground transportation should be able to get travelers between downtown D.C. and Dulles in less time, especially during non-peak hours.

Jay Labov, Vienna

DG: Civic leaders and transportation officials expect the Silver Line to multi-task, which seems only right for a project that will cost nearly $6 billion by the time both phases are done.

The goals include the easing of traffic conditions along the Dulles Toll Road corridor by diverting some commuters to transit as well as offering travelers an alternative way of getting to and from the airport.

But over the past decade, project documents have always included other objectives as well, and none is defined as the “primary” mission for the rail link that has become known as the Silver Line.

For example, many of those responsible for financing the line’s first phase are focused on what the four new stations in Tysons Corner will mean to the economic future of Northern Virginia. And they don’t limit their vision to moving residents, workers and shoppers via transit. They also want to use the stations to shape development.

Labov is asking good, practical questions about getting to and from the airport.

There certainly will be many airport travelers who will prefer not to take the train. Chances of that increased when the authority that operates the airport and is managing the rail line’s construction decided to put the airport train station far from the terminal to save money.

A veteran traveler would know that the trip along the Dulles Airport Access highway is almost always a speedy one, and for many would often be competitive with a train trip in terms of both rapidity and reliability.

But Dulles draws passengers from a big region. A traveler from Bowie, for example, might not want to fight traffic on Route 50 and the Capital Beltway to reach the Dulles access road. Perhaps that traveler will go to a Metrorail station in Prince George’s County instead. Another traveler might prefer the Metrorail trip when trying to get between Reagan National Airport and Dulles.

The goal wasn’t to replace one travel method with another, but to create a new option. Just how popular that option will become is a story that will play out over several decades.