ANAHEIM >> Southern California leaders are anticipating a $2 billion windfall in transportation dollars from the state’s expanding cap-and-trade program that could be used for building more pay lanes or funding the county’s growing bus and rail system.

As dollars from the gasoline tax drop, transportation planners will turn to polluters — including oil companies — who will begin to pay into the state’s cap-and-trade program in 2015 set up in a market-based exchange.

The program was part of the state’s AB 32 laws passed in 2006 to substantially reduce greenhouse gases that cause global warming.

State officials predict the cap-and-trade fund will grow from about $1 billion to $5 billion next year, when oil companies begin to pay for carbon emissions. Of that, about 40 percent would flow to transportation for everything from a rail line into LAX, to light-rail across the foothills to Claremont to pay lanes on the 105, 134, 5 and 405 freeways.

“This is huge,” said Hasan Ikhrata, executive director of the Southern California Association of Governments. “This is the only new source of transportation funding we have.” Ikhrata was part of 1,000 leaders from seven Southern California counties who came here Friday to discuss transportation solutions as part of an annual Mobility 21 Summit.

“Traffic doesn’t care about borders, so we need to work together as a region to expand our transportation options and help people get around more easily,” said Los Angeles Mayor Eric Garcetti, a guest speaker.

“The regional approach is the only way for us to move forward. Traffic has never been worse. It is probably the No. 1 concern for all of our constituents,” said Garcetti.

The group calls Southern California one of the most congested regions in the country. Motorists driving in the Los Angeles-Long Beach-Orange County region waste 502 million hours each year in traffic in total, or about 61 hours per year per automobile commuter. Drivers in the Inland Empire waste 51 million hours per year or 38 hours per automobile commuter, according to the Mobility 21 group.

To address basic needs, Southern California needs $26.6 billion to repair state highways, $44.3 billion for streets and $1.8 billion for local bridge work in the next 10 years, the group estimated.

When Garcetti was asked what projects Los Angeles would apply for under new cap and trade transportation funds, he answered: “It should not just be for capital projects. I would hope it is also for operational costs.”

Garcetti, who is also chairman of the Los Angeles County Metropolitan Transportation Authority known as Metro, was referring to the giant agency’s $36 million operating deficit. Although the board voted to raise fares effective Sept. 15, it won’t be enough to lift the agency out of the red. Some have suggested raising fares again in 2015 or 2016.

“I want to keep those fares down,” he said.

About 60 percent of cap-and-trade funds will be reserved for transportation, including 25 percent for the California high-speed rail project. The remainder can be spent on local transportation projects and 5 percent can go toward ongoing transit operations, said Brian Kelly, secretary of the California State Transportation Agency, a luncheon speaker.

New monies — about $216 million — has been allotted for bicycle and pedestrian projects throughout the state, he said. Of the 148 projects funded, 82 of them were in Southern California, Kelly said.

Cap and trade remains controversial because it could translate into higher gasoline prices, many speakers said Friday. Another perhaps more touchy potential revenue source is a mileage-based tax on motorists, something Kelly said the state is exploring.

“We need a long-term funding source for California to meet our demands,” he said.