HARTFORD, Conn. (CBSNewYork)Connecticut Gov. Dannel Malloy is rolling out his transportation overhaul with plans to replace the Hartford Viaduct, the elevated portion of I-84 into the capital city.

The project will cost $3.4 billion, but will have a projected return to the state of $9 billion to $10 billion, Malloy told WCBS 880 Connecticut Bureau Chief Fran Schniedau.

“What we are doing in Connecticut is saying that we’re going to build a first-class transportation system,” the governor said. “We’re studying the biggest projects to make sure that our return on investment justififes the expense.”

The governor said today 170,00 cars a day cross the Hartford Viaduct, more than twice the number originally projected 55 years ago when the elevated, now-deteriorating 2.5-mile stretch was built. It was designed to have a 50-year service life.

The long-term upgrade statewide calls for a $100 billion investment over 30 years.

“We’ve already taken the first step, and that’s to devote one-half cent of our sales tax for transportation use,” Malloy said. “That will actually pay for the first eights year of this program.”