The Georgia Department of Transportation will extend the process for selecting a builder and operator of the Ga. 400 toll lanes by about four months after one of the finalists for the project dropped out.

GDOT says the extension will allow the remaining two finalists to strengthen their proposals.

Using what’s called a procurement process, GDOT had planned to select a contractor for the work in January. Now, the decision will come in the second quarter of next year.

“We have two strong teams,” GDOT Chief Engineer Meg Pirkle told the State Transportation Board on Wednesday. “We have confidence we will have a very competitive procurement.”

The move also will affect the timeline for proposed toll lanes on the top half of I-285. That procurement process — originally scheduled to begin this year — will be postponed until after the Ga. 400 contract is awarded. That will allow the firms vying for the Ga. 400 lanes to bid on the I-285 project.

GDOT plans to build 16 miles of toll lanes along Ga. 400 in Fulton and Forsyth counties. It plans to build nearly 40 miles of toll lanes on the top half of the Perimeter.

The lanes on both highways would be built and operated by private companies, which would set the tolls. They’re part of a planned 120-mile network of metro Atlanta toll lanes.

Both projects have seen their schedules pushed back several times. Last year, GDOT reshuffled the timelines for the Ga. 400 and I-285 lanes, the new I-285 interchange at I-20 west of Atlanta and truck lanes on I-75 between Macon and McDonough.

GDOT originally solicited contractors for the Ga. 400 lanes two years ago. But the State Transportation Board rejected the lone responsive bid because it far exceeded the project’s $1.7 billion budget.

GDOT tried again and announced three finalists in September: Express 400 Partners, Georgia Express Link Partners and SR 400 Peach Partners. Each finalist is a partnership of numerous firms that would be involved in the financing, construction and operation of the lanes.

Express 400 Partners has now dropped out of consideration. Pirkle said the firm’s membership “altered unexpectedly.” The remaining firms must submit detailed proposals by January.

GDOT expects the Ga. 400 lanes to be open by 2031. They originally were to be under construction in 2021 and open next year.

Despite the delays, GDOT is replacing three bridges along Ga. 400 as a prelude to construction of the new lanes.