I don’t think it has run since Covid

Is there a reasoning behind this limit?

How fast will it be:

We won’t know for sure until they can do testing and validation, since a lot is dependent on how traffic signals are configured and how much things like pedestrians and intersections slow it down. The MTA estimates it will take about an hour to complete the full 16 miles, tho I suspect the Bethesda>Silver Spring and CP Metro>New Carrollton bits will be substantially faster than the Silver Spring>CP Metro stretch. So let’s say on average it will be about half the speed of metro trains as another commenter suggested.

What is the wait between trains

The website says they aim for trains every 7.5 min during rush hour and every 12 min off peak, but I am told that those numbers are still only estimates and may change when they can actually start running trains and get a sense of the reality of the operating conditions. In the future I believe it’s designed to hypothetically be able to have trains as frequently as every 5 min.

Medical Center to Forest Glenn

Almost certainly faster to incorporate the purple line, the section from Bethesda to Silver Spring is nearly completely grade separated from traffic so it will be the fastest part of the whole line.

How do transfers work

At Bethesda, the purple line station will be a bit underground, and they are building a new southern entrance to the metro station to directly link to the purple line and provide better access into the metro from that part of Bethesda.

At Silver Spring, it will be on the top floor of the adjacent transit center, and they plan to construct a new bridge from the purple line station to the Red line, with stairs leading down to the red line platform from above. This overpass isn’t present on the online renderings but I have had it confirmed to me multiple times by people on the purple line team that it is planned.

At College Park and New Carrollton it will have its own platform somewhat adjacent to the bus bays, you can see those layouts on the website under construction>plans.

How do fares work

You will need to tap out of the metro to get to the purple line, but the purple line will almost certainly be SmarTrip compatible. What exactly the fares would be or if discounts for Metro/Bus > Purple Line transfers will be offered is still up in the air.

Light rail was meant for politicians to be able to say “look, we built a light rail” and not much else. It was built on the cheapest route they could find which happened to be on an old railroad that didn’t serve many dense areas. The metro was built in a similar way, it just happens that the old rail corridor used for metro happened to serve denser areas than the light rail

From innovation center you can catch a bus that takes you to the awesome Uvar Hazi branch of the air and space museum, featuring a Blackbird (fastest plane ever built), a Concorde, a real space shuttle, the Enola Gay (the plane which dropped the atomic bomb on Hiroshima), and much more.

MARC train to DC, Metro to Airport

There are two MARC train lines that go from Baltimore to DC: The Penn line is the main one, it goes from Penn Station to DC via New Carrollton, and runs every day with decent enough frequency.

The Camden line is the other option, it runs limit rush-hour-only service between Camden Yards and DC via Greenbelt/College Park. It is slower than the Penn line, but depending on your location in Baltimore and timing of your flight might be easier to get to.

For both lines, the fastest way to the airport is ride to Union Station, then take the Red Line to Metro Center, and change to the blue line for National Airport.

For the Penn line, if you don’t want to deal with changing at Metro center, you can also get off at New Carrollton and catch a blue line train directly to National airport, tho it will take longer than the Union Station option.

Normally if you took the Camden line you’d be able to catch a direct yellow line at Greenbelt or College Park, but the entire yellow line is currently closed for repairs to the bridge over the Potomac, so if you do the Camden line it’s easiest to just go all the way to Union.

Also, normally there wouldn’t be any blue line trains at New Carrollton, but due to the Yellow line construction, blue line service was significantly beefed up, with every other blue line train going to New Carrollton instead of Largo.

Lmk if you have any questions.