They were forced to evacuate the train and walk along the tracks.
"We're sorry about it, we're very frustrated along with it and we have higher expectations for our level of service than we've been able to provide," said RTD spokesperson Nate Currey. "We're working closely with our partners to get these kinks worked out as quickly as possible."
The problems have ranged from power issues, to mechanical failures, to acts of nature like a lightning strike that shutdown the rail line on June 13.
"The unfortunate part about the last few months is that they've all been individual instances that have had nothing relatively to do with one another, but all back to back to back so it seems like the train is just breaking down constantly," said Currey.
Rail Crossing Technology Issues
One of the larger ongoing problems involves cross arm malfunctions at rail crossings along the new commuter line.
The Public Utilities Commission (PUC) is requiring flaggers to be stationed at each crossing to help direct traffic in the event of a signal malfunction until the system is working properly.
The requirement will remain in effect until the transportation agencies new, first-of-its-kind Positive Train Control system has been certified and operates correctly.
RTD said the Positive Train Control is more high tech than the existing Active Train Control, which uses an electric current in the tracks and the approaching trains own axles to complete a circuit which then activates crossing arms, flashing lights and warning bells.
The new system is supposed to work wirelessly and communicate with the train control center.
Currey said RTD hopes to have the system fixed within a month and a half, but if the problem persists it could impact other rail lines currently being constructed.
Potential G Line Delays
The G Line or Gold Line between Union Station and Wheat Ridge, passing through northwest Denver, Adams County and Arvada, is expected to open early this Fall in October of 2016.
RTD said right now the project is on schedule, but if the Positive Train Control System bugs aren't worked out soon, it could delay the G line opening.
"If for some reason that doesn't get fixed on the A Line over the next couple months, by the end of the fall or early winter, that would be an issue here," said Currey.
Despite the issues, RTD said more people are riding the A Line and ridership figures continue to grow each week.
According to data provided by RTD, 15,860 people rode the train the first week, 16,775 the fourth week and 16,951 the seventh week.
Currey said the only time the A Line saw a slight decline was after passengers were stranded on the tracks back in May.
"Every week after its rebounded and every single week other than it has been increasing," he said. "We understand -- I mean shoot if you're having that big of issues you're going to question whether or not it's smart to take the train."