A Los Angeles subway project designed to link three rail lines in downtown Los Angeles will open a year later than expected, according to transit officials.

The new opening date for Metro's ambitious Regional Connector is December 2021, six months after the deadline established by federal officials and a year after the agency's target date of December 2020, the Los Angeles Times reported. The opening date shift will not affect federal funding for the project, which totals about $830 million, Metro officials told the Times.

"We still have four years to go," project manager Gary Baker said in remarks reported by The Times. "But I'm confident that we'll be able to successfully meet our schedule."

Construction work should reach the halfway point early next year, he added.

Crews have encountered setbacks beneath the streets of downtown Los Angeles, including utility problems, such as aging water pipes and fragile utility lines. The utilities needed reinforcement before digging could begin for the subway project, leading to delays.

The Regional Connector's $1.75 billion budget is 28 percent higher than originally forecast.

The proposed line will be 1.9 miles long and include two light-rail tunnels between Union Station and the 7th Street/Metro Center stop in the Financial District. The Blue, Gold and Expo lines will be converted to two routes that will allow passengers to ride from Santa Monica to East Los Angeles, and from Azusa to Long Beach, without transferring.

The plan calls for three new stations at First Street and Central Avenue (Little Tokyo/Arts District Station), Second Streets and Broadway (Historic Broadway Station) and Second Place and Hope Street (Grand Avenue Arts/Bunker Hill Station).

The tunnels are expected to boost rail ridership by 17,000 trips a day and shave as much as 20 minutes from some journeys.

NBC4's Jonathan Lloyd contributed to this report.