By Marshall Zelinger, KUSA-9News
Once again, RTD is asking federal authorities to allow its trains to Denver International Airport and Westminster to keep running while it continues work on crossing-gate issues.
The transit agency currently has until Sunday under a previous waiver to get approval from the Federal Railroad Administration (FRA) that the warning system on its A and B commuter-rail lines is functioning within regulations.
The waivers allow the trains to run while RTD and its contractor…