COLUMBIA — Legislators agree South Carolina’s roads and bridges are in dire need of work. How to pay for it is another matter.

The Department of Transportation estimates it needs nearly double the amount currently spent on state-maintained roads – $1.5 billion yearly over the next 20 years – just to bring them to “good” condition.

The idea of raising the state’s 16-cents-per-gallon fuel tax, unchanged since 1987, has been tossed around in recent years. But in a state controlled by Republicans who like to boast yearly of cutting taxes, legislators contend that’s not even a possibility.

In her State of the State address, Gov. Nikki Haley urged the Legislature to fix the state’s crumbling infrastructure, calling it a safety and economic necessity.

“The citizens of South Carolina deserve to drive on roads that aren’t littered with potholes and on bridges they know won’t fall down. It’s a core function of government. But it’s also an economic development issue,” she said, quickly adding, “But I will not – not now, not ever – support raising the gas tax. The answer to our infrastructure problems is not to tax our people more; it’s to spend their money smarter.”

But her suggestions fund a tiny fraction of the need.

In her budget proposal, she recommends re-directing $4.3 million of fuel taxes currently diverted to other agencies and using $10 million of capital reserves for road work. She also wants the majority of additional money that money that comes in above current revenue projections for 2013-14 put toward roads, but only after taking $26 million off the top for income tax cuts. While the amount depends on the economy, she said that could give DOT $77 million.

A bill sponsored by House Speaker Bobby Harrell would shift all of the roughly $100 million collected through the state sales tax on vehicles – which is capped at $300 – specifically to road work.

More than 50 Republicans have signed on to the bill introduced Wednesday. But that idea has previously died in the Senate.

DOT director Robert St. Onge said his job is to “manage the decline of the state highway system.”

That includes nearly 41,500 highway miles and 8,400 bridges, making South Carolina’s system the nation’s fourth-largest, funded in part by the fourth-lowest state tax. Of the $1.5 billion the DOT expects to collect next fiscal year, 60 percent comes from federal taxes.

St. Onge said he realizes legislators aren’t going to double his budget.

A nonprofit coalition is urging legislators to spend $6 billion over the next 10 to 15 years on the most critical projects statewide: $2.8 billion on interstate widening, $2 billion on bridges and $1.2 billion on resurfacing.

The report issued this week by the S.C. Alliance to Fix Our Roads – made up of business leaders, associations and chambers of commerce – is based on the DOT’s own priority list, though it seeks immediate improvement of Interstate 26, calling that vital to tourism and port traffic.

Rick Todd, an alliance member, said the $1.5 billion price tag “blows people away,” so the alliance wanted to break it down. Still, that’s $600 million a year to get it done in a decade.

“It is ambitious, but at least somebody’s put a plan on the table,” said Todd, director of the state Trucking Association. “As crowded as the roads are now, I don’t want to think about how congested and inefficient they’ll be in 10 to 15 years. We’ve got to start.”

While no lawmaker’s suggestions come anywhere close to the funding requests, Todd applauded the willingness of Republican leaders to redirect money toward highway needs.

“We haven’t been able to get this much focus and talk in a long, long time,” he said.