Travelers will be able to take commuter rail from Denver Union Station to Denver International Airport starting April 22, 2016, at a cost of $9. The estimated travel time for the 23-mile trek is 37 minutes. . . . The ticket price is for a regional pass that allows for multiple trips on a single day. . . . the downtown-to-DIA train is known as the RTD University of Colorado A Line[.]From here.