Yes, Subway restaurants are relatively common on college and university campuses. The company was operating 515 college locations worldwide as of December 2013. More than 200 of those college Subway restaurants were located in the United States as of 2010.
These totals represent only a percentage of all Subway restaurants - they don't include the many restaurants that are located in business districts near universities. Campuses are desirable locations for quick-service restaurants because they draw a large number of people who eat at many different times of day. Subway representatives say their restaurants fit well with a college audience because they sell healthy and portable food and tend to be open late at night. In 2013, a new location at the UC Irvine campus improved sales by 70% over the previous sandwich shop in the same space.