Here's the short story about Maryland's planning program. It was almost eliminated in the early 1990s. The program itself has origins both at the University of Maryland at Baltimore where the professional masters was housed and the College Park campus where BA and a non professional MA degree was offered. Although saved from elimination, the program did lose its undergraduate and non professional masters degrees and moved from the College of Behavioral and Social Sciences into the College of Architecture (now Architecture, Planning & Preservation).
Maryland's professional planning program is now the only full time accredited planning program in the Washington area. Virginia Tech (and before the University of Virginia) offers a masters degree in Northern Virginia, but it is a evening program. Since staving off elimination, the program has actually stabalized itself and added a Ph.D. program. In addition, the program serves as the nucleus of the unviversity wide Center for Smart Growth. The addition of nationally known faculty such as Qing Shen and Gerritt Knaap has buttressed the programs reputation.
The fact that they are going to have a university wide transportation initiative is heartening. Maryland's civil engineering department has always had a strong transportation program and the logistics program with the business school is one of the tops in that nation. However, interdisciplinary research was never really strong at Maryland.
As for the professional masters degree program it is a Master of COMMUNITY Planning. This is important, this is a program that is involved in the community. It also means yo have a good chance of getting a job in Maryland if that is your goal. It is also a relatively small program which had less than 50 student enrolled. Also, while the program can be completed part time the majority of the students are enrolled full time.
Now as for transportation. GMU, has a interdisciplinary MA degree housed within it's Public Policy Program. It has the advantage of being a transportation program with multiple transportation faculty. It also is designed for the working professional with all courses held at a Metro friendly location.
I would advise anyone wanting to do transportation to go to a more established program. MIT, contrary to popular belief does not have a full time transportation faculty member in the planning department. Programs with well regarded programs in transportation include Berkeley, UCLA, USC, Georgia Tech, North Carolina, and Pennsylvania.