The Sierra Club report released Tuesday, which examines 50 of the country’s best and worst transportation projects, says the privately run, four-lane toll highway cutting through the Maine woods would have negative impacts on air and water quality and critical wildlife habitat. It says a freight rail line parallel to the proposed route could reduce vehicle miles traveled and redirect public investments toward passenger and commuter rail.

The report notes that similar highway proposals have been studied and rejected numerous times in the past.

A financial feasibility study by the Maine Department of Transportation awaits proposals showing where the east-west highway’s connections to existing highways would be.

MDOT spokesman Ted Talbot said the state was still awaiting specifics including where the proposed highway would connect to existing Maine roads. He said Tuesday the department did not have a time frame or deadline for that information.

“Until we see those we can’t do a reliable feasibility study,” Talbot said.

The leading supporter of the project, Peter Vigue, chairman of the Cianbro Corp. construction company in Maine, did not immediately respond to a message seeking comment on the report. But he told lawmakers earlier this year that the highway route would revitalize Maine ports and rail systems, create jobs and open Maine industries to global trade while opening up a long-term utility and communications corridor.