Plans for toll lanes on Ga. 400 got a boost Tuesday when the U.S. Department of Transportation announced a $184.1 million grant for the project.

Georgia plans to build 17 miles of express toll lanes in Fulton and Forsyth counties. Construction is expected to start in 2021.

The lanes are included in the state’s Major Mobility Investment Program – 11 major road projects to be paid for in part with money from a gas tax increase and other revenue approved by the General Assembly in 2015. The total cost of the Ga. 400 lanes is expected to be about $1.8 billion.

U.S. Rep. Rob Woodall, R-Lawrenceville, called the federal grant “further proof of the amazing things we’re getting done together.”

The Ga. 400 project is part of a planned 120-mile system of toll lanes across metro Atlanta.