This horn is painful. Not the sound pressure level, but the muffled blast is grating. Kinda like listening to Fran. The Penn Line of the MARC Train Service operates primarily between . Line include areas surrounding Washington D. C. such as Gaithersburg, Rockville, and. 5 S Summit Ave Gaithersburg, MD Gaithersburg MARC Station in Gaithersburg, reviews by real people. Yelp is a fun and easy way to find, recommend and talk about what's great and not so great. See 20 photos and 2 tips from visitors to Gaithersburg MARC Station. "Try the sandies from the station deli lady. They are awesome!". 1 Mile to MARC Gaithersburg. Easy Highway and Transit Access. 24 Hour Fitness Center. Extra Storage Available. Business Center with Wi-Fi. Music Room. This horn is painful. Not the sound pressure level, but the muffled blast is grating. Kinda like listening to Fran.