Blue Line riders who were already smarting from the introduction of this summer's "Rush Plus" change to Metrorail service will be facing even worse service in Northern Virginia when the Silver Line starts running.

Blue Line trains will operate every 12 minutes during rush periods, according to a new report slated to be presented to Metro's board of directors Thursday. Under Rush Plus, which began in June, the longest wait during peak periods is 12 minutes but some trains are still scheduled to arrive every six minutes. Previously all trains were about six minutes apart during the morning and evening peaks.

Metro says the new 12-minute waits are better than the original plan to have trains run only every 14 minutes during peak periods. The agency also noted it will be running more eight-car trains to help ease crowding on what riders now dub the Blue Crush.

For Blue Line riders downtown or even in Prince George's County, though, the impact of the new service pattern won't be so bad. The transit agency has decided to run the Silver Line to Largo Town Center instead of stopping at Stadium-Armory, as first reported by The Washington Post, because it does not think a pocket track can accommodate trains switching direction there. But that means Blue Line riders traveling to and from the eastern end of the line can use those Silver Line trains, too, which will operate every six minutes during peak periods.

The big change is slated to begin by the end of 2013 when operations on the first 11 miles of the Silver Line are expected to start.