State and local officials Wednesday signed an agreement to study bus rapid transit on the top half of the Perimeter.

The transit service would operate in new toll lanes the Georgia Department of Transportation plans to build in coming years. The bus rapid transit route would stretch from H.E. Holmes station on the west side of Atlanta to the Indian Creek station in DeKalb County.

The toll lanes will cost an estimated $6.1 billion, and bus rapid transit would cost nearly $1 billion more to build, operate and maintain over 20 years.

The study would cost up to $16.2 million, with MARTA paying most of the tab. Among other things, it will determine the best places to establish transit stations along the Perimeter.

The transit service would cross numerous jurisdictional boundaries. On Wednesday representatives of GDOT, MARTA, the Atlanta Regional Commission, the Atlanta-Region Transit Link Authority and Cobb, DeKalb, Fulton and Gwinnett counties signed an agreement to study the project.

The signers hailed the agreement as a milestone in regional cooperation.

“Cobb County is not an island of itself,” said Cobb Commission Chair Lisa Cupid. “The better we are as a region the better we are as a county.”

Plans for station locations along the route are expected to be finished this year.