The I-270/US 15 Corridor is a vital link to other highways in the Maryland and Washington, DC region. I-270 begins at the Capital Beltway (I-495) and extends north to I-70 in Frederick, Maryland. The corridor acts as an artery between the nation's capital and points north and west.

The study corridor is heavily used by commercial vehicles, as well as commuters. The level of performance for the roadway is currently sub-par, with motorists wasting precious time and gasoline sitting in traffic on a daily basis.

In the 1970s, Montgomery County officials developed a general alignment for the Corridor Cities Transitway (CCT) and the project was included in the Montgomery County Master Plan and Plan updates over the years. Well over 50 percent of the transitway alignment has been actively preserved or reserved by Montgomery County as the land around it has developed. The alignment identified by the County in their Master Plan was adopted by the Maryland Transit Administration (MTA) when they initiated study of transit improvements to serve the "corridor cities" in the mid-1990s.

In the mid-1990s, MTA and the State Highway Administration (SHA) initiated a corridor study to investigate different combinations of highway and transit improvements that could reduce congestion, increase mobility and improve safety conditions along the heavily traveled I-270/US 15 Corridor in Montgomery and Frederick Counties. Over the course of the study's twelve years, engineers and planners analyzed a range of alternatives to determine their environmental and transportation system effects and performance. SHA and MTA published the results of these analyses in several environmental documents, developed in accordance with the National Environmental Policy Act (NEPA) of 1969. The first of these was a Draft Environmental Impact Statement (DEIS) published in May 2002. The second document was an Alternatives Analysis/Environmental Assessment published in May 2009.

After more than a decade working together on a single multi-modal project, the highway and transit elements of the I-270/US 15 Multi-Modal Corridor Study will go forward as separate, but coordinated, projects. The decision to proceed on independent, but coordinated, study tracks reflects the complexity of developing a multi-modal project with other federal and state agencies while also addressing distinct community and environmental needs and effects.  The first independent action that was taken for the CCT was to complete a the 2010 Supplemental Environmental Assessment which focused on alignment modifications near Crown Farm, Life Sciences Center and Kentlands in Gaithersburg, and other new developments.  The CCT project design elements will continue to evolve as the project progresses.

Currently, commuters are presented with several modal options, such as Commuter Bus, MARC, Metrorail, and Ridesharing. However, the corridor is well known as a regional commuting nightmare, with severe congestion at many locations, and the impact is expected to become more widespread as development in the area continues to flourish.