The Tappan Zee Bridge replacement project was approved Thursday for a $1.6 billion Transportation Infrastructure Finance and Innovation Act (TIFIA) loan, a development that allows officials to finalize plans for toll increases that will pay for the $3.9 billion effort.

The loan was the largest of its kind the U.S. Department of Transportation has ever awarded.

Thursday's announcement comes more than a year after New York State Thruway Authority submitted a $1.58 billion loan request to the TIFIA, program. It also comes days after Standard & Poor's gave the New York State Thruway Authority an A long-term bond rating, down from the A+ rating it had.

The downgrade is probably related to the uncertainty over how much tolls will increase to pay for the replacement project. The Thruway Authority will issue $2.4 billion in bonds to cover Tappan Zee replacement costs but a more detailed financial plan for the project has not been released.

The TIFIA loan was approved "following a thorough assessment" that included a full creditworthiness review, the DOT said in a statement.

State officials said the interest rate for the loan will be set when the agreement is finalized in December.

The consortium composed by Fluor Enterprises, Inc., American Bridge Company, Granite Construction Northeast, Inc., and Traylor Bros., Inc., was selected for the multi-billion dollar, design-build contract for the new Tappan Zee Hudson River Crossing Project in December 2012.