State lawmakers received few answers Wednesday as they grilled the state transportation commissioner at a public hearing on a proposal to bring back tolls to Connecticut roads.

Questions about where the tolls would go, how much revenue they would generate and how much drivers would pay remained unanswered.

What Commissioner James Redeker did say was that without new revenue, more than $4 billion in highway projects won't happen.

"Electronic tolls would be a new tool in Connecticut's toolbox at a time when our transportation infrastructure needs outstrip our ability to make absolutely necessary investments," he said.

Toll proposals have failed repeatedly in Hartford, but Republican lawmakers seemed open to at least studying the idea at Wednesday's hearing.

The DOT estimates that a toll study would cost about $10 million. Installing them afterward might cost $300 million. Revenue proposals without tolls include a 7-cent hike in the state's gas tax or other expenses imposed on commuters.

"The Department of Transportation will be forced to implement unprecedented bus and rail fare increases," Redeker said. "And service cuts that will impact hundreds of thousands of commuters in Connecticut."

Another obstacle is drivers themselves.

"I'm not a fan of tolls anywhere," said Hanno Bartsch, a Stamford driver on Interstate 95.