ATLANTA — Four groups have been shortlisted for consideration to design, build and partially finance the $950 million, 30-mile Northwest Corridor project along Interstate Highways 75 and 575 in Cobb and Cherokee counties, including a Marietta company.

Construction on the project is targeted to begin in summer 2014 with a completion date of spring 2018, said Darryl VanMeter, state innovative program delivery engineer for the Georgia Department of Transportation.

The project will build two new, reversible lanes along the west side of I-75 between its interchanges with I-285 and I-575. The lanes will be separate from the existing interstate and carry traffic south during morning commute hours and north in the evenings. North of the I-575 interchange one new, reversible lane will be added in the I-75 center median to Hickory Grove Road, and a similar new lane will extend along I-575 to Sixes Road.

Toll amounts have not been set but will vary depending on traffic volume. The toll lanes, which are intended to ease congestion, will only be open during peak travel times.

Gov. Nathan Deal has been clear to point out that the Cobb/Cherokee project is different than the toll lanes introduced in Gwinnett County in that these will be new lanes.

The project is being paid for with $300 million of state gasoline taxes carried over from previous years to the project and $200 million from GDOT’s construction budget. The state is also applying for a $270 million low-interest federal loan.

“The contractor is going to finance for us 10 to 20 percent for the duration of the construction contract,” VanMeter said. “Our estimate is that’s between $80 (million) and $160 million.”

Toll revenues will go to the state, not the contractor. The $160 million will be repaid with bonds at the end of the project, VanMeter said.

The four teams will be asked to submit final proposals to the state in December, with a contractor selected next summer.

The groups are C.W. Matthews Contracting Co. Inc. of Marietta and the Michael Baker Corp.; Fluor-Lane LLC of Greenville, S.C.; Georgia Transportation Partners, comprising Bechtel Infrastructure Corp. of Reston, VA, Kiewit Infrastructure South Co., Dewberry and Davis, LLC, and STV Inc.; and Northwest Express Road Builders, comprising Archer Western Contractors of Atlanta, The Hubbard Group and Parsons Corp.

DOT staff will hold an informational meeting about the project from 6 to 8 p.m. Tuesday in the meeting room of the Cobb County Board of Commissioners, located at 100 Cherokee St. in Marietta.