State regulators Wednesday delivered a major blow to RTD, denying its request to change the timing of crossing gates on several of the metro area’s commuter rail lines as well as turning down a planned resumption of full testing on the as-yet-unopened G-Line.

The unanimous decision by the Colorado Public Utilities Commission came at a morning meeting of the agency’s three commissioners, who concluded that the Regional Transportation District’s at-grade crossing plan did not enhance safety for those driving or biking over the tracks.

“We’re disappointed in the decision,” RTD spokesman Nate Currey said shortly after the denials came down. “We feel the system is where it needs to be. But it is up to the PUC to decide on their own.”

The PUC, along with the Federal Railroad Administration, must approve operational changes at the dozen at-grade crossings on the University of Colorado A-Line to Denver International Airport and the B-Line to Westminster. Until they do, flaggers are required at crossings 24 hours a day.

This past April, The Denver Post calculated that RTD’s private sector partner, Denver Transit Partners, had spent more than $6 million to staff the A-Line’s 11 crossings with flaggers and police officers during its first year of operation.

Currey said RTD, along with Denver Transit Partners, will continue working with PUC’s technical committee to come up with a solution to the new wireless signal technology RTD is trying to integrate into its commuter rail lines.

“We are committed to the system we have — we’ve spent millions of dollars on it,” he said.

Until a fix is found, business owners and commuters on the west side of town are left wondering when the train to Wheat Ridge and Arvada will start rolling. Currey said Wednesday’s decision makes it certain that the G-Line won’t begin carrying passengers before the end of the year.

“The G-Line will wait as it has been,” he said.

Arvada City Councilman John Marriott, who sits on the city’s G-Line advisory committee, called the added delay “disappointing and annoying.”

“As a city, we’ve invested some of the city’s money into a transit hub and train platform,” he said.

Marriott said he hears from constituents who regularly ask when the G-Line will make its debut and worries whether “windows of opportunity” may close for businesses looking to set up operations in the city.

Just last week, a group of transit experts and land-use planners from around the world toured a number of new apartment complexes — like 152-unit Park Place Olde Town and 352-unit Solana Olde Town Station Apartments in the heart of Arvada — as part of the Rail-Volution national transit conference held in Denver.

Arvada Mayor Marc Williams apologized to the group as he touted Olde Town Arvada as a model for transit-oriented development.

“I’m sorry you couldn’t ride the train out here, as was the original plan,” he said to the group gathered in the Hilton Garden Inn, which opened as Arvada’s first hotel earlier this year.

PUC commissioners expressed concern Wednesday that RTD’s solution to the crossing arm issue, which would leave gates in the down position up to 20 seconds longer than federal regulations permit, could result in impatient motorists trying to find a way around the roadblock and meeting tragedy on the tracks.

RTD says the new wireless technology it is trying to implement at crossings on the A-Line, B-Line and G-Line has never been used before in the United States and the additional close time is needed to make the system work properly.

PUC Chairman Jeffrey Ackermann wondered if the agency was taking the right approach with its crossing signal technology.

“Maybe it’s time to try something different,” he said.