Metro officials said Thursday that they have no way to ease the 12-minute waits between trains that thousands of Blue Line riders will suffer once the Silver Line opens.

"I'm sorry we don't have another solution, but we simply have not been able to find one that makes financial or time sense," said Washington Metropolitan Area Transit Authority board member Mary Hynes, who urged Metro to do more to alleviate the long wait times by running only eight-car trains on the line to move more people.

The arrival of the Silver Line, expected late this year, means that Metro's Rosslyn tunnel will be stuffed with Silver, Orange and Blue line cars, and Metro staff proposed a service plan Thursday that would mean 12-minute waits between rush-hour Blue Line trains. The plan would help speed up close to 400,000 trips on the Metro system while creating more crowds and longer waits for more than 80,000 trips, according to a Metro analysis.

Metro officials said Thursday that they had no better solution.

"After a lot of work on staff's part and work on the jurisdictions' part, it doesn't appear that there is a good bus alternative that will move people along quickly," Hynes said. "There's several tens of thousands of people who ride that route. I really think it's something the board should care about."

Hynes, an Arlington County Board member who represents Virginia on the Metro board, questioned why Metro was planning to put only $1 million per year toward a proposed new tunnel for the Blue Line, which would cost $1.5 billion to build.

But Metro General Manager Richard Sarles said the $1 million in the agency's proposed budget would pay for planning and studies for a new connection and that the agency didn't have the money yet to push for construction, which he hoped could start by 2020.

"On Blue Line, there's no easy solution. The buses and that sort of thing just didn't help," Sarles said. "So we're looking at something that would be a major infrastructure improvement, we're talking possible tunneling here. This is something you have to do a lot of planning, environmental work, engineering. So those things we have in the plan, we start that."

A board committee voted to approve the plan that included the 12-minute waits.