Almost two years after it was supposed to open, the G Line is one step closer to actually carrying passengers throughout the metro area.

The Regional Transportation District and its light rail contractor Denver Transit Partners has received approval from the Federal Railroad Administration (FRA) to begin the next phase of testing on the G Line. Starting July 20, testing is ramping up and will soon simulate the full daily service schedule of nearly 21 consecutive hours each day.

Limited testing along the forthcoming 11.2-mile line between Union Station and Wheat Ridge began last fall and has been underway between 8 a.m. and 6 p.m. 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.

“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 Dave Genova, RTD CEO and general manager.

The trains must run the schedule successfully for 21 days before the line will open to passengers. An opening date for the G Line has not yet been announced.

“The best case is we have 21 days of testing and then we open,” said Arvada Mayor Marc Williams, who has been vocal about his disappointment in the delays of the line opening.

The G Line is part of Regional Transit District’s 2004 voter-approved FasTracks plan to expand transit across the Denver metro region. It is an 11.2-mile electric commuter rail transit line that will connect Denver Union Station to Wheat Ridge, passing through northwest Denver, Adams County and Arvada. There are eight stations: Denver Union Station, 41st/Fox, Pecos, Federal, Gold Strike, Olde Town Arvada, Arvada Ridge and Ward Road.

Construction on the G Line was completed in 2016, but has remained stuck in the testing phase with no opening date.

The gate-crossing technology, which caused the hold up on the line opening, 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 commuter train B Line, to Westminster.

Though there is still no official opening date, city of Arvada staff has started to coordinate with RTD to plan opening celebrations.

“We want it open as soon as possible,” said Lorraine Anderson, RTD director for District L, which includes Arvada and Southern Adams County.

During this phase of testing, the public is asked to be alert, abide by all safety signage at railroad crossings, respect potential closures of railroad or at-grade crossings along the alignment, and not attempt to view testing by accessing construction areas at stations and various locations along the tracks.

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, people should exercise caution as they move and drive through the area.

When the G Line officially opens — date 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.

During testing, train operators will continue to sound their horns when passing through intersections. Until quiet zones have been approved by the FRA, the use of train horns and other safety measures will make drivers and pedestrians aware of train movements.

RTD will announce the start of quiet zones for the G Line once such approvals from the FRA are in place.

Also during testing, crossing gates may stay down for extended periods of time. Attendants will continue to be stationed at all G Line grade crossings until RTD receives the necessary state and federal approvals to remove them.