Metro image shows route of Silver Line between Wiehle-Reston East and Largo Town Center stations.

Among the comments that came in Friday afternoon from the many Metro riders caught up in delays on the Blue and Orange lines were some that predicted even worse delays and crowding once the Silver Line service begins. We’ve talked a lot about what the new line will mean to riders under normal circumstances, but what about during a disruption?

On Friday, thousands of riders were delayed and train service was disrupted because an insulator on the third rail near Rosslyn was sparking. The electrical problem is not unusual, and it will happen again.

Metro was forced to shut down a portion of the track serving two lines at the height of the afternoon rush. As a result, trains going to and from Virginia took turns using the one open track. In the central zone where the Blue and Orange lines operate in the same tunnel, Metro schedules 26 trains per hour, the maximum safe service it says is possible. Trains are crowded under normal circumstances, and the effects of any delay quickly reverberate up and down the lines, leading to crowding in both directions on the platforms and the backed-up trains.

Eastern Market sign Silver Line brings more choices. And more problems? (Robert Thomson – The Washington Post)

Virginia-bound or Maryland-bound commuters who wanted to stick with transit rather than hail a cab could endure the wait for a train; try to catch a bus, such as the 38B from Farragut Square across the Key Bridge to Arlington County; or, if you’re a Blue Line rider heading to Virginia, get to L’Enfant Plaza and board a Yellow Line train toward Huntington.

There are problems with those alternatives. The buses, even on rush hour frequency, may be overwhelmed by commuters fleeing a Metrorail delay. And if you’re already in a downtown station during a delay, you’ll have to wait a while for a train to reach L’Enfant Plaza.

Add the Silver Line to the mix, and what would you get?

In a Twitter exchange on Friday afternoon, I was sharing short takes on this with @roadtohell, who wrote in part: “This will only get worse with the Silver Line … There will arguably be more people waiting at already overcrowded platforms in the troubled area, no?”

He’s right to worry about whether the extra line will make these painful situations even more painful, but not all riders would be affected the same way. A key factor is that going east from downtown to Maryland, there still will be two terminal destinations. Going west from downtown to Virginia, we’ll go from two to three terminal destinations.

Blue Line. Once the Silver Line starts, they will have two fewer trains per hour during the rush. That’s one train every 12 minutes. Now, if you’re commute is between Capitol South and Foggy Bottom, you will be no worse off than today, because you can take either an Orange, Blue or Silver Line train. It adds up to the same number of trains as today in that zone. But if you work near Farragut West, and park your car at Franconia-Springfield station, or take a bus from there, a disruption means you’re likely to wait even longer to board even more crowded trains. If you work on Capitol Hill and park a car or take a bus at Largo Town Center, you should be better off than you would have been on Friday, because you could take either a Blue or Silver Line train.

If you’re a Farragut West rider, and conditions look as bad as they did on Friday, remember that those two trains per hour you lost went over to become Rush Plus Yellow Line trains. So that might create more incentive to go to L’Enfant Plaza and board a Yellow Line train to Virginia — assuming you can get to L’Enfant Plaza.

Orange Line. The Rush Plus Orange Line trains will be eliminated. If you’re the commuter from Capitol South heading back to New Carrollton, you’ll have to pass up the Blue and Silver Line trains and wait till an Orange Line train arrives. On Friday afternoon, the Orange Line riders were skipping only the Blue Line trains. If you’re at Farragut West heading for Vienna, you’re sharing that platform with commuters heading in the direction of Franconia-Springfield on the Blue Line and for Tysons Corner or Wiehle-Reston East on the Silver Line. At first, there may not be many more people than today, because many of those Silver Line passengers will be former Orange Line riders, shifting over.

To reach Vienna, you’ll still have to pass up the Silver and Blue Line trains. That is, unless you want to board a Silver Line train and get off at East Falls Church. You would wait there for the next Orange Line train, which by then may be less crowded than the one you would have waited for at Farragut West.

Silver Line. In this disruption scenario, it will be important for riders to know where the Silver Line goes — that it’s not just a train to serve five new stations in Fairfax County, that it connects the Reston area with Largo Town Center via downtown Washington. On those extra crowded platforms, you’ll want to make sure that if you can take it, you take it. Ten Silver Line trains are scheduled to run each hour during the rush.

So how much of an extra problem an individual rider has during a future disruption will vary. But what about the question posed by @roadtohell on whether the platforms will be even more crowded? Not so much at first, because of the number of commuters who will simply be switching from the Orange Line to the Silver Line, and because of the number of people in the central zone who can take any train, as long as the entire trip is in the central zone.

But the planners involved don’t see the Silver Line as a mere Orange Line alternative. They very much want to draw new riders to Metrorail. My guess is that this added ridership will become most problematic on the westbound platforms during an afternoon rush hour disruption, because there will be an extra destination (Wiehle Avenue). Riders will linger on the westbound platforms, because they will wait for their own trains to the outer destinations. While their waiting for their own color to show up, more and more riders will be arriving at the downtown stations, prepared to wait with them.

This is your silver lining: The new rail cars on order should start entering service late this year. They will create more eight-car trains, and the new cars should have fewer of the door and brake problems that knock trains out of service at the height of rush hour.

Still, as long as trains have moving parts and roll over tracks, there will be breakdowns, and riders will endure experiences similar to Friday’s. We’ll discover quickly enough in the coming months whether those experiences will be worse or less worse than before the Silver Line.

Join me at noon Monday for our weekly online discussion about the D.C. area’s traffic and transit issues.