Washington residents soon will have a new way to get to Baltimore or Baltimore/Washington International Thurgood Marshall Airport on the weekends.

Maryland's MARC commuter train is extending its Penn Line service to Saturday and Sunday, thanks to a $60 million cash infusion from Gov. Martin O'Malley's transportation package.

State officials say they're still negotiating the details with its operator, Amtrak, but that they expect to offer nine round trips between Baltimore and Washington on Saturdays and Sundays by the end of the year.

"I'm guessing it's going to be a matter of months. It won't happen tomorrow," said Terry Owens, a spokesman for the Maryland Transit Administration, which oversees MARC.

The Penn Line is the most popular of MARC's three lines and averages 24,000 riders a day, Owens said. An exact schedule and price tag for the state are still being worked out with Amtrak, Owens said. Ticket prices for riders will be the same as those for weekday rides.

Offering weekend service has been part of MARC's growth plan since 2007, but the state didn't have the money until now. The package signed Thursday raises $1.2 billion for transportation projects by indexing the state's flat 23.5-cents-per-gallon gasoline tax to the cost of inflation and adding a new 1 percent wholesale tax on gas, which will cost Maryland drivers an extra 4 cents per gallon starting July 1.

"I think [the weekend service] is fantastic news," said Rafael Guroian, a MARC rider and member of the Riders Advisory Council. "It's an enhancement to the MARC service that is long overdue. It's a great first step to building a Maryland regional rail system that we're going to be needing in the next 20 and 30 years."

Owens said the state doesn't have projections for how many people will ride the line on the weekends but said he thought it would be helpful for tourists trying to make it into D.C. from BWI Airport and commuters who need to work on the weekends.

"I think that what we're going to see is people using it to work on weekends," Guroian said. "Many people do. I'm certainly one of them."

The money also will pay for two new weekday round trips on MARC's Camden Line. The package will fund $40 million for 10 new locomotives to replace aging, unreliable machines.