Denver’s Regional Transportation District (RTD) received approval from the Federal Railroad Administration (FRA) to begin the next phase of testing on the G Line. Beginning late last week, testing is ramping up and will soon simulate the full daily service schedule of nearly 21 consecutive hours each day.

The authorization given to RTD and its contractor, Denver Transit Partners (DTP), represents another significant step forward in the process to open the commuter rail line for passenger service.

Limited testing along the forthcoming 11.2-mile line between Union Station and Wheat Ridge began last fall and has been underway between on weekdays since the start of this year. That process has examined the communication signaling along the line, as well as the effectiveness of the communication technology in place at each of the G Line’s 16 at-grade railroad crossings. The gate-crossing technology is the same as that used along two additional lines originating in downtown Denver: the University of Colorado A Line to Denver International Airport, and the B Line to Westminster.

“We are pleased to have arrived at this phase in the testing schedule, and we continue to appreciate the patience of the public, businesses and leaders in the communities along the G Line as we work through all of the necessary details,” said RTD CEO/GM Dave Genova. An opening date for the G Line has not yet been announced.

As many as three trains will be running on the alignment every day, for an initial period intended to help train operators become familiar with the line. During this time frame, trains will operate every half hour starting as early as 3:30 a.m. and extending through 1 a.m. the following day. With more trains running for longer periods of time throughout the day, the RTD is urging the public to exercise caution as they move and drive through the area.

The official start to the next phase of G Line testing — simulating full passenger service — will follow this initial period. A date for the start of that phase has not been determined.

When the G Line officially opens — which also has yet to be determined — trains will run from 4 a.m. to 12:30 a.m., with 15-minute frequency between 6 a.m. and 6:30 p.m. and every 30 minutes during off-peak hours.

The line is a segment of RTD’s FasTracks program, a voter-approved transit expansion initiative to build new commuter rail and light rail, bus rapid transit service and new parking spaces; redevelop Denver Union Station; and redirect bus service to better connect the eight-county district.