(Ben Claassen III/For Express) (Ben Claassen III/For Express)

Sometimes I worry I’m not enough of a transit dork to be writing this column. And then I’ll have an experience like the one I had Monday. A friend asked when weekend MARC service was scheduled to start, and I excitedly shrieked back, “In less than a week — there’s even a countdown clock!”

Yes, I’ve been constantly checking the Maryland Transit Administration’s website and watching the minutes tick toward 7:10 a.m. Saturday. That’s when the commuter system’s first D.C.-bound trip of the morning will commence. It’s one of nine round-trip train rides scheduled for that day. There will be six more on Sunday.

Instead of just being work buddies, Baltimore and D.C. will now get to spend their downtime together. With just a $7 one-way ticket, folks can start their morning with blue bucks in Eastern Market and have crab cakes for lunch at Lexington Market. They can catch exhibits at both the Smithsonian American Art Museum and the American Visionary Art Museum. Or they can knock back an Ozzy at The Brewer’s Art without worrying about the drive home to Dupont.

And, most important, they can be spontaneous about it. With Amtrak, it’s possible to get reasonable fares between the two cities if you plan well in advance. But if you want to pick up tickets day of? Expect to spend up to $50. Just think about how many Berger cookies that could buy.

I wouldn’t be surprised if the Charm City delicacy makes an appearance along with the assorted transportation dignitaries slated to be at Union Station for Saturday morning’s launch.

For the event, MARC is pulling out all the stops. (Although not quite stopping at all of them. Weekend trains are only on the Penn Line route and will be skipping Seabrook, Edgewood, Aberdeen and Perryville. Martin State Airport will have limited service.)

A “rolling press conference” — that’s open to the public — will take place on the 9:02 a.m. train to Baltimore’s Penn Station, where the city’s mayor, Stephanie Rawlings-Blake, will be waiting to say hi.

Who will she be greeting? No one really knows yet. MTA predicts the weekend service will be popular with leisure travelers headed to and from BWI, commuters who don’t just work Monday through Friday and sports fans. Passenger data will help determine whether any tweaks should be made to the schedule, which will be revised in six months.

Expect me to report on those changes in the dorkiest way possible.

That’s the Ticket

Taking MARC to Baltimore this weekend? Here’s what you need to know:

-You can download the schedule at mta.maryland.gov. The last train on Saturday leaves Baltimore at 9:15 p.m. and D.C. at 10:35 p.m. (On Sunday, it’s 5:30 p.m. and 7 p.m.)

-Penn Station is sandwiched between Baltimore’s Station North and Mount Vernon neighborhoods. Both are worth a visit, but you can also head to each side of the station to pick up the Charm City Circulator’s Purple Route, which offers free(!) rides to the Inner Harbor.

-Remember that your SmarTrip card works for bus, light-rail and Metro trips in Baltimore, too.

-Swing by the Bromo Seltzer Arts Tower (at 21 S. Eutaw St.) to see how artists have re-envisioned nearby crosswalks as hopscotch games and opening zippers. Headed back after dark? Check out the Washington Monument — the original one — which is all lit up for the holidays.