Before we get too far, there needs to be some background here.

The MARC Camden Line runs on CSX tracks, not Amtrak tracks like the Penn Line. That means you're contending with freight train traffic... and many of the railroads want to run longer freight trains.

The line is double-track (YAY!) but has some areas of contention (from north to south, skipping some small track branches):

• HB TOWER Interlocking (read: track switch) east of Raven's Stadium, which lets trains go through the Howard Street Tunnel, over to Locus Point, or down to DC.
• BAILEY Interlocking, which lets trains go north, east, or south depending on direction of travel... and pick a track.
• CARROL Interlocking, which lets trains go around and possibly connect to the ol' B&O Museum, head down to Curtis bay, or continue south through the Mount Winans train yard.
• ST DENIS Interlocking, as we move down south, before the actual MARC station. This allows trains to hit the right track to go to Western Maryland via Elicott City, or continue south. The MARC stop requires some track protection.
• Further south you have DORSEY and the MARC station just north of it.
• You got JESSUP Interlocking and the MARC station north of it, which is a good spot to catch some track switching action (and not a good station to actually, you know, catch a train to DC from). It feeds into a major CSX yard for use in offloading cars. The other end of the yard has PA TOWER and FT MEADE JUNCTION Interlockings north of the Savage train station.
• You got SAVAGE Interlocking south of that, which just lets trains switch tracks.
• South you got two stations, the Laurel Racetrack (two doors wide) and Laurel itself. Further south, Muirkirk.
• The next full track switch you got is AMMENDALE Interlocking. Gee, that's a lot of track to have a train on one side.
• You got Greenbelt station, that lets MARC trains offload on "pocket" tracks... and get trapped with too long freight trains. College Park and Riverdale stations are after that.
• Then you get to RIVERDALE PARK and JD interlockings, which lets trains go down further south through Virginia.
• And finally, before you hit Union Station, you got F Tower, which lets trains ether switch to Amtrak trackage or curve back northwest to QN tower.

I think you can see why trains get delayed.

The only benefit here is that Dorsey and Savage are closest to Columbia, where a TON of people live. Dorsey's close to BWI (and it's pay-to-park station) and Savage is close to Odenton (and it's free-but-full station).