Idaho lawmakers are gearing up to spend the final few weeks of the legislative session focused on transportation funding possibilities, including a key tool the Legislature hasn't leveraged since 2005.

Last week, Sen. Bert Brackett, a Republican from Rogerson and chairman of the Senate Transportation Committee, introduced two pieces of legislation to allow the state to borrow $300 million in bonds for road projects and repay it with future federal-aid highway payments. Both bills will likely be heard in the Senate Transportation Committee on Thursday.

Those bonds are known as "Grant Anticipation Revenue Bonds" - or GARVEE bonds.

To address major issues like capacity expansion, safety, mitigation and congestion, lawmakers are looking to those federal bonds.

One of the two bills Brackett introduced asks for about $500 million total: $300 million of which is GARVEE bonding and $200 million would come from general state bonding and the surplus eliminator. It can also be used more flexibly.

"None of these things are going to solve it completely but they're all tools that we should consider using," the senator added.

Idaho first used these bonds in 2005 to fund transportation upgrade projects throughout the state - such as the widening of Interstate 84 between Caldwell and Meridian and the Highway 16 extension.

"It's the largest infrastructure program in state history," Idaho Transportation Department spokesman Vincent Trimboli said.

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Many states use these bonds to fund transportation projects due to a lack of available cash to pay for the entire project upfront.

"The GARVEE projects we did in the late 2000's and early this decade were all expansion projects, all aimed at safety and mobility. They were projects that without that money we couldn't have done," Trimboli added.

Trimboli says ITD bonded for about $857.6 million with 59 projects in six corridors throughout Idaho. ITD says those projects were finished in late 2015/early 2016 and won't be paid off until 2031.

"We actually use money from our federal allotment and we pay just over $57 million a year back to pay off those bondings," Trimboli told KTVB.

"It's working remarkably well and so I think there should be some comfort level with adding a few more [bonds]," Sen. Brackett added."This will go where the need is."

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Brackett says early on, infrastructure wasn't a major issue legislators were planning on tackling this session, but priorities have shifted, particularly because of the harsh winter we have experienced across Idaho.

In most need of GARVEE funding is the corridor of Interstate 84 in Canyon County from Franklin to Karcher, Brackett said.

"That is our highest priority so that's where I would anticipate $150 million of that [$300 million] would go," he added.

But Brackett feels the Idaho Transportation Board should choose which projects this bonding goes toward.

"As opposed to the Legislature picking projects. We've tried that and there were problems with that," Brackett said.

The senator says the $300 million proposal is a fallback if the roughly $500 million bill fails.