Only one logical response to the lack of train cars for the Silver Line: delay the opening
The Metro subway system in the DC metropolitan area is already stressed for 5 reasons:
1. crossing limitations between Northern Virginia and DC, which has led to the creation of the new Rush+ system where some blue line trains run across the yellow line crossing instead of through Rosslyn;
2. an aging car fleet which also means many more broken down trains during rush periods;
3. speed and operating restrictions in place until problems with the signaling system are fully corrected (it was failures in the signaling system that led to the fatal crash in June 2009 between the Fort Totten and Takoma Metro Stations on the red line);
4. capacity constraints at stations in the core of the center city (especially at Gallery Place, which was designed in a manner that makes transferring between the lines downstairs and the lines upstairs more difficult);
5. constant system reconstruction (maintenance) as the system ages is resulting in constant station and line closures (mostly on weekends).
While the capacity constraint issue has no real solution on the horizon other than the creation of a separated and parallel "blue line"--which could have been built as part of the extension of the system through the addition of the silver line but isn't--the fact that the system won't have enough train cars by the time the Silver Line is supposed to open is a real problem.
Note that Toronto has a similar problem with capacity at the core and so there continues to be talk about creating a Downtown Relief Line (see "Toronto transit: ‘Downtown’ relief line could be the subway suburbanites crave" from the Toronto Star).
Yesterday, the Examiner reported ("Silver Line to use old rail cars initially") on this problem, which is in part fallout from the Japanese earthquake and tsunami, which impacted manufacturing of the cars, and the delays in opening a test facility.
People won't like my suggestion, but delaying the opening, given all the other issues, not to mention difficulties in hiring more personnel ("WMATA to raise fares, hire 1,000 workers and increase parking rates" from the Washington Post) makes the most sense.
Putting more stress on an already stressed system (including the safety and operations issues) by needing to keep almost all cars in constant operation, having few cars in reserve, is a really bad idea.
Open the new line once there are enough cars on hand to support adequate provision of trains on all lines, with an adequate inventory of cars in reserve.