Denver Union Station is bustling with activity on early evening of February 8, 2019. In the foreground on Track 8, a B-line RTD train waits for departure to Westminster. Track 7 is currently vacant, but will soon see the arrival of another test train on the G-line from Wheat Ridge, and a spare RTD Hyundai-Rotem EMU train sits on Track 6. Over on Track 5, Amtrak’s Winter Park Express ski train has just arrived as passengers scramble to gather up their skis and other belongings from the baggage section of the Superliner cars. Sitting next to No. 1006 is Amtrak No. 6, the eastbound California Zephyr making its station stop. Not seen behind the tall Amtrak trains is RTD’s A-line trains to Denver International Airport, arriving and departing every 15 minutes from Track Nos. 1 and 2.