Testing on Denver’s newest rail line, the G Line from downtown to Arvada and Wheat Ridge, resumed Wednesday — but when it will start ferrying passengers along its 11-mile length is unknown.

“We’re not sure when it will open,” RTD spokesman Nate Currey said Wednesday morning, shortly before the first test train operated by Denver Transit Partners, RTD’s private contractor, passed through the station at 61st Avenue and Federal, warning bells clanging and horns blaring.

We hope and expect that it could be this year, but it could be 2018,” Currey said.

It’s up to the Colorado Public Utilities Commission (PUC) and the Federal Railroad Administration (FRA) to determine when passenger service can begin.

Read more at Denver Business Journal.