Gasoline taxes that for nearly half a century have paid for the federal share of highway and bridge construction can no longer be counted on to raise enough money to keep the U.S. transportation system moving, LaHood said in an interview with The Associated Press.

"We should look at the vehicular miles program where people are actually clocked on the number of miles that they traveled," the former Illinois Republican lawmaker said.

Most transportation experts see a vehicle miles traveled tax as a long-term solution, but Congress is being urged to move in that direction now by funding pilot projects.

The idea also is gaining ground in several states. Governors in Idaho and Rhode Island are talking about such programs, and a North Carolina panel suggested in December the state start charging motorists a quarter-cent for every mile as a substitute for the gas tax.

A tentative plan in Massachusetts to use GPS chips in vehicles to charge motorists by the mile has drawn complaints from drivers who say it's an Orwellian intrusion by government into the lives of citizens. Other motorists say it eliminates an incentive to drive more fuel-efficient cars since gas guzzlers will be taxed at the same rate as fuel sippers.

Besides a vehicle miles traveled tax, more tolls for highways and bridges and more government partnerships with business to finance transportation projects are other funding options, LaHood, one of two Republicans in President Barack Obama's Cabinet, said in the interview Thursday.

"What I see this administration doing is this - thinking outside the box on how we fund our infrastructure in America," he said.