WASHINGTON Another key group in the debate over future highway funding has weighed in with a report that warns of a looming $11 billion hole in federal highway funds and says the growing interest in tolls and private leases of roads wont generate enough money to meet the nations short- or long-term transportation needs.

Instead, the federal gas tax of 18.4 cents per gallon, last raised 14 years ago, would have to go up at least 3 cents by 2009 and 7 cents more by 2015 just to maintain the current highway system and keep pace with the fast-rising cost of roads, according to the American Association of State Highway and Transportation Officials.

One seemingly increasingly popular solution to road-funding woes involves state and local governments adding toll lanes or leasing toll roads to private companies. But tolling isnt going to solve the problem, says the association.

Indiana has leased the Indiana Toll Road for $3.85 billion for 75 years; Texas wants to build 4,000 miles of privately financed toll roads, and Pennsylvania and New Jersey are considering leasing portions of their toll roads to private companies.

In 2005, tolling earned $7.7 billion, which was 5 percent of highway revenues nationally, AASHTO reported. Tolling could increase to 9 percent of highway funds over the next decade, a significant amount but not a "silver bullet" to fix the country's transportation funding problems, said Victor Mendez, director of the Arizona Department of Transportation and president of AASHTO.

Pete Rahn, director of the Missouri Department of Transportation, said states are looking for innovative ways to use the marketplace. "But the reality is, no matter how far we try to stretch these resources, we're not even coming close to dealing with the real needs of the critical roads that are the lifeblood of this country," he said.

The report is the first of six AASHTO plans to provide to the congressionally chartered panel analyzing the countrys future transportation needs. The last similar comprehensive study was issued in 1979 and called for deregulation of the aviation, rail and trucking industries and major investments in transportation.

The AASHTO report said the capacity of the interstate system will have to double during the next 50 years and the number of people riding public transportation should double within 20 years. Railways must be prepared to handle a 63 percent increase in freight by 2035, according to the association's estimates.

The half-century old interstate system is in danger of being overwhelmed by long-term neglect, a steady increase in the number of drivers, a stagnant source of funding and rampant inflation of road-building costs, according to AASHTO.

The biggest immediate hurdle to improving roads is that federal gas taxes, which pay for more than 45 percent of the nations transportation infrastructure, are not even sufficient to cover the spending authorized in the 2005 federal transportation law. Federal gas taxes will fall $11 billion short of planned road projects by 2009, but the gap could be as big as $19 billion the following year, the association said.