Fly-over lanes would connect I-15 to U.S. 95 so motorists using the toll lanes could avoid onramps and offramps at the Spaghetti Bowl.

Private investment would cover nearly all of the costs of the project. And free lanes would continue to be maintained along those routes.

"There has been a lot of talk, there have been a lot of meetings, here is an opportunity to try it," Transportation Department Director Susan Martinovich told the department's Public Private Partnership Advisory Panel on Thursday.

If the demonstration project didn't work, she said, the state could walk away from the toll roads.

The Transportation Department board will decide whether to continue to pursue the project.

Still, toll roads would be years away. The Legislature, which doesn't convene again until 2009, would have to pass laws allowing tolls and automated enforcement.

During the 2007 Legislature a proposal to allow tolls in Nevada failed to get a committee hearing.

The demonstration project would offer a maximum toll of 30 cents a mile, or a total of $5.70 to travel all 19 miles during peak hours. Tolls would vary depending on the time of day and could drop to 5 cents a mile during off-peak hours.

Analysts from the investment bank Goldman Sachs told the subcommittee that the demonstration project would cost an estimated $1.4 billion, of which 88 percent could be paid for by private entities.

The public-private partnership would then allow private investors to reap the proceeds from the toll lanes to pay back their investment at a fair rate of return, which was judged to be 13 percent.

Anything earned on the roads above that amount would be shared with the state.

It could take up to 50 years for investors to reach the goals of their investment, at which time the toll lanes would be turned over to the state.

There are several similar public-private partnerships throughout the nation, including in Virginia, Texas and Illinois.

Contact reporter Francis McCabe at fmccabe@reviewjournal.com or 702-387-2904.