Metro riders are seen aboard a train at the L'Enfant Plaza Metro station in Washington. (Evelyn Hockstein/For The Washington Post)

For Metro, buffeted by criticism over fatal safety lapses and gross financial bungling, a bit of good news has arrived. Transportation officials in Maryland, Virginia and the District have indicated that they are willing to pony up hundreds of millions of dollars for the transit agency to buy cutting-edge subway cars.

Mortimer L. Downey, chairman of Metro’s board of directors, said Friday that he has been told that he will receive a letter next week signed by the transportation chiefs in the three jurisdictions, formalizing a decision — “in principle” — to finance the purchase of 220 new subway cars, which Metro says will cost $614 million.

Still to be determined, though, is whether the jurisdictions also will foot the bill for the major upgrades in subway infrastructure that would be required to accommodate all eight-car trains on weekdays from 5 to 9:30 a.m. and from 3 to 7 p.m. The price tag for those improvements is $856 million, according to the transit agency.

“We’ve said we need to go forward” with buying the new cars, Maryland Transportation Secretary Peter K. Rahn told the Greater Washington Board of Trade on Thursday, referring to himself and his regional counterparts, Virginia Transportation Secretary Aubrey Layne and the District’s transportation director, Leif A. Dormsjo.

“The question is, how do you use these new cars?” Rahn said.

Since Jan. 12, when an electrical malfunction on tracks near Metro’s L’Enfant Plaza station filled a tunnel with smoke, causing the death of a train passenger, the transit agency has been sharply criticized for failing to keep the rail system in safe working order.

Before the jurisdictions would finance the entire eight-car train plan — a combined $1.47 billion for new cars and related infrastructure growth — “we believe [Metro] needs to be concentrating on a state of good repair,” Rahn told the board of trade. “It doesn’t make a lot of sense to continue to expand when the system you have is deteriorating.”

Downey said the letter from the transportation chiefs will instruct Metro to prepare a detailed written analysis in the next few months, laying out options for how the 220 cars could be used. One of the options will be the eight-car train proposal, he said. But Rahn and his colleagues ultimately could decide to go in a less expensive direction.

“I’m very happy,” Downey said. “It’s better than them telling us that the option of eight-car trains is completely off the table. And it shows that they’re thinking it through.”

The eight-car train proposal has been the centerpiece of Metro’s long-term plan to increase ridership capacity, which it says is essential to the Washington area’s economic growth. Acquiring the 220 cars is just the first step.

Metro has about 1,130 subway cars, purchased in six batches over the past four decades, as the rail system, which opened in 1976, has grown. The life span of a car is typically 40 years, with an expensive overhaul being performed after 20 years. Metro’s oldest batch, 300 cars of the so-called 1000 series, were built in the mid-1970s and are ready to be retired.

The agency also has nearly 500 cars dating to the 1980s, about 300 cars bought in the 1990s and early 2000s and 84 cars manufactured in the mid-2000s. More than half the cars already have undergone mid-life overhauls.

Metro hopes to buy more technologically advanced cars built by the Kawasaki Rail Car Co. in Lincoln, Neb. Funding has been approved for the bulk of the cars, and the agency expects production to begin this spring.

Those cars are due to arrive at various times before the end of 2017.

Metro wants to use 300 of the newly purchased cars to replace cars that are due to be scrapped or overhauled in the coming years. They would also be used to supply the new Silver Line.

To complete its plan to acquire the advanced cars — by buying 220 more — Metro needs a funding commitment from the three jurisdictions before its purchase options expire in July. What’s in doubt is whether those cars will be used the way Metro has longed hoped — to ease crowding by doing away with six-car train during rush hours.

The cars would arrive in 2018, Metro says.

Because an all eight-car system would place a much greater physical demand on the rail system, Metro says it would need the $856 million for related infrastructure upgrades to boost the subway’s electrical supply, expand stations and beef up track equipment.

But if the region’s transportation chiefs decide against the infrastructure investment, Downey said, most of the 220 new cars of the 7000 series could be used as replacements for older cars. “They’re lousy cars, is one good reason to do it,” he said of the plan to get rid of the cars in favor of the new series. He said Metro could avoid the expense of a mid-life overhaul of some older cars, due in early 2020s, by replacing them with the newer cars.

“To me, it’s a good step forward,” Downey said of the jurisdictions’ provisional decision to finance the purchase. “As time goes by, and we get our house in order, we’ll eventually see where we are in terms of how we use them.”

Staff writer Robert Thomson contributed to this story.