RTD's A Line connects Union Station to the Denver International Airport. 

(Courtesy Denver Regional Transportation District)

RTD’s train from Denver to DIA, the A Line, got another lease on life Thursday from the Federal Railroad Administration despite ongoing problems with its crossing gates.

The transit district received another 90-day wavier from the FRA as it continues trying to fix software and hardware issues that have caused delays, as well as the continued posting of crossing guards at gates that are supposed to work automatically.

As we reported earlier, the gates at each crossing are controlled by something called positive train control, which Congress has mandated for all commuter trains in the country. The technology uses GPS and other wireless systems to prevent accidents.

RTD's CEO, Dave Genova, said the FRA won't allow the G line in Wheat Ridge to open until the A Line issue is resolved.

“They want us to be able to show significant progress on the crossing timing improvements, or get all the way through the certification process with it before they'll allow us to go back out and test, continue testing on the G Line," he said.

The G, or Gold, Line, which will run from Union Station to Wheat Ridge, was supposed to open in 2016. RTD even began testing last fall before A and B line issues prompted the agency to put the 11-mile route on hold.

Genova said they still expect that to happen in 2017, but there's no exact date yet.