With the White House and some in Congress against a gas-tax hike, lawmakers drafting a long-term highway-transit bill are hunting for other funding sources. An option gaining serious attention involves enhancing the Transportation Infrastructure Finance and Innovation Act program, which provides federal loans and loan guarantees for major projects.

TIFIA’s appeal is its multiplier effect: A modest direct federal subsidy can support big loans, leveraging non-federal dollars to yield packages funding billion-dollar projects. TIFIA, launched in 1998, has a solid following. The Federal Highway Administration reports $6.3 billion in active TIFIA loans for 17 projects with a total cost of $23.4 billion.

Demand for new TIFIA aid is strong. FHWA has received 34 proposals seeking $14 billion in 2011 TIFIA assistance, which would help finance $48.2 billion in projects. FHWA officials aren’t yet certain how much TIFIA funding they will have from Congress this year. The program’s 2010 level of $122 million could yield $1.2 billion in loans, or less than 10% of the sum states sought for 2011.

Senate Environment and Public Works Committee Chairman Barbara Boxer (D-Calif.) wants to expand TIFIA in the highway bill she is preparing. “I just think [TIFIA is] an exciting option for us,” she said at a March 9 hearing. House Transportation and Infrastructure Committee Chairman John Mica (R-Fla.) has said he will look at expanding and modifying TIFIA in his own highway-transit bill.

Speaking to Boxer’s panel, Dept. of Transportation Secretary Ray LaHood said, “We like the TIFIA program very much.” DOT’s 2012 budget seeks to more than triple TIFIA, to $450 million. That direct funding would produce $4.5 billion in TIFIA loans and help finance $13 billion in projects, says Chris Bertram, DOT’s chief financial officer. TIFIA aid is limited to a third of a project’s total price tag.

TIFIA isn’t a panacea. States prefer federal grants to TIFIA loans, which must be repaid with interest. Even $13 billion in annual TIFIA aid combined with current Highway Trust Fund revenue falls far short of funding the six-year, $556-billion bill that DOT has proposed.