Transportation funding is likely to be a hot topic in next year’s General Assembly session, and a pair of lawmakers plan to reintroduce what could be a game-changing proposal.

A constitutional amendment drafted by Sen. James C. Rosapepe (D-Dist. 21) of College Park and Del. Brian J. Feldman (D-Dist. 15) of Potomac would allow the governor and lawmakers to piece together specific plans to fund transportation projects and put them to referendum for voter approval.

“Lots of states, lots of communities, lots of cities do this all the time,” Rosapepe said. “It’s pretty normal.”

Voters in 18 states have approved more than 70 such projects during the past three years, Rosapepe said. He and Feldman introduced their amendment during the August special session, but lawmakers focused only on gambling and pit bull-related issues, and the proposal did not advance.

Transportation advocates point to success stories in places such as Denver and Seattle, where voters approved sales-tax increases to fund rail systems in 2004 and 2008, respectively.

But a statewide vote in Georgia this summer illustrates the potential difficulties of such a process, said David Goldberg, spokesman for the Washington, D.C.-based nonprofit Transportation for America.

Legislation passed in Georgia in 2010 divided the state into 12 regions, each of which had its own set of predetermined road improvement and public transportation projects. Georgians went to the polls in July to vote on a penny increase in the sales tax, which was projected to raise more than $18 billion for transportation by 2022.

But the referendum passed in only three regions, where the tax is expected to raise about $1.5 billion for 871 projects, according to the state’s Department of Transportation.

Goldberg says the number of projects in Georgia might have been too large and varied to appeal to voters.

“It looked like a big grab bag,” he said.

With such referendums, the more local, the better, Goldberg said. “People see transportation through a local and pretty personal prism” and need some sense of the benefit to them, he said.

The Seattle plan passed because voters could clearly see the purpose — bringing rail to an area that didn’t have it — and saw it as transformative, Goldberg said.

“Voters have to be a bit inspired,” he said, adding routine maintenance to bridges and roads was a tougher sell. An earlier, mixed plan that included highways, as well as transit, was rejected by Seattle voters, he said.

But major, new projects aren’t the only ones voters are willing to support. Michigan voters agreed in August to continue paying local millage taxes — tied to property values — to fund various public transportation initiatives. Projects ranged from small, local bus service for senior citizens to full bus operations in cities like Ann Arbor, said Megan Owens, executive director of the Detroit-based nonprofit Transportation Riders United.

In Maine, residents routinely vote on bond packages for highway improvement, as often as every two years, according to Maria Fuentes, executive director of the Maine Better Transportation Association. A $51 million bond will be on the ballot in November, she said.

Similar referendums could prove to be a useful tool in Maryland, Rosapepe said. “[But] under the Maryland Constitution, we don’t have the authority to do it.”

The amendment allows for the practice, which could include issuing bonds or creating new revenue sources, but puts no stipulations on the size or scope of the projects in question.

As prices at the pump rose during the 2012 regular session, lawmakers did not act on a proposal by Gov. Martin O’Malley (D) to apply the state’s 6 percent sales tax to gasoline, which was projected to raise about $613 million for transportation infrastructure. The state’s flat, 23.5-cent-per-gallon gas tax has not been increased since 1992.

Since 1984, hundreds of millions of dollars have been taken from the state’s Transportation Trust Fund to balance the state’s budget.

More than $500 million in Maryland Department of Transportation funds have been repaid, but $947.5 million in Highway User Revenues — intended to pay for local road repairs — have not, according to the state’s Blue Ribbon Commission on Transportation Funding.

The amendment also would restrict such transfers to emergency situations like urgent public health threats or invasion by a foreign army, as long as there is a plan to pay back the money within five years.

But past transfers are one reason why the referendum proposal is a bad idea, according to Christopher Summers, president of the conservative Maryland Public Policy Institute.

“Motorists have already paid for these projects,” Summers said, adding lawmakers should explore other ways to find the funding, such as privatization or making unpopular cuts in other areas of government.

Rosapepe said he believed the governor and legislative leaders want to pass a transportation funding package in the next session, and he hoped the amendment would pass regardless, so it can be a tool available for future use.

“I think it’s a very interesting proposal, very worthy of consideration,” said Mahlon “Lon” G. Anderson, managing director of public affairs for AAA Mid-Atlantic and a member of the Blue Ribbon Commission.

Like many new and different proposals, it might take time to pass, but it’s worth trying a new approach after years of “abject failure” to adequately fund transportation in Maryland, Anderson said.

Anderson also has called for the state to dedicate a nearly $500 million surplus from fiscal 2012 to the trust fund.

Another commission member, former state senator Donald C. Fry, also spoke favorably of the proposed amendment.

In additon to protecting the fund against future transfers, putting the projects to vote could restore public trust, said Fry, who is now president and CEO of the Greater Baltimore Committee.

“Now, there’s a lack of confidence that the money will be used for transportation projects,” he said.