Once the Maryland Department of Transportation received legislative authority in 2013 to proceed with P3 projects, it wasted no time in implementing regulations and beginning the process that has now led to the largest design-build-finance-operate-maintain transit agreement in the United States. The $2.4 billion Purple Line Light Rail System will run 16 miles between the Maryland suburbs of Bethesda and New Carrollton with 21 stations, providing a direct link to the Metrorail lines and connecting to the MARC train, Amtrak and local bus services. MDOT’s Purple Line is the latest in a long history of successful transportation design-build projects in Maryland.