This year, RTD will have opened up five projects in the metro area – including the new RTD A-Line to the airport.
The newest line, the B-Line from Westminster to downtown Denver, debuts in July.
It begins in the area of 71st Avenue and Federal Boulevard, and ends at Union Station.
The new line will feature the same commuter rail technology that is used on the A-Line, which has had numerous problems since its debut.
RTD says technology is to blame.
"There’s a different aspect to the system when it goes live and there are things that need to be tweaked and enhanced that we couldn’t have found during testing," RTD spokesperson Tara Battale said.
Battale says because the technology is new, additional problems arise when the train is “live” versus when it was being tested.
More than 18,000 passengers ride the line per day.
RTD says it plans to learn from the problems from the A-Line to better understand what the A-line may encounter.
The B-Line debuts July 25.
Two additional lines will open by the end of the year.