ALEXANDRIA, Va. – Why are Congress’ popularity ratings still in the cellar? Look no further than House Transportation Committee Chair James Oberstar’s response to the Minneapolis tragedy: add 5 cents to the current 18.4 cent-per-gallon federal gasoline tax, and dedicate the proceeds to repairing bridge infrastructure.

The Minnesota Democrat’s plan seems straightforward, except that Americans are coming to realize the government’s fiscal infrastructure is deceptively constructed.

For example, nearly one-fifth of federal gasoline taxes motorists pay is steered toward mass transit and “transportation enhancements” like bike trails – such diversions are even higher for state gas levies.

Touted as the solution to traffic jams, mass transit – chiefly rail-oriented – has usually flopped. According to federal data, even though inflation-adjusted funding for transit has doubled over the last 25 years, only about 2 percent of urban travel occurs on rail, bus or other non-automotive means: a share that’s barely budged except in dense downtowns. So much for alleviating crowded interstates.

Worse, American Enterprise Institute scholar Joel Schwartz calculates that every ton of ozone-damaging pollutants avoided because of rail costs $1 million. Simply optimizing automobile traffic signals to reduce wait times would be more effective. No wonder: Based on statistics compiled by the Center for the American Dream, rail construction projects tend to suffer five times more in cost overruns than highways.

And far from sticking it to Big Oil by combating the “almighty automobile,” most transit initiatives merely derail programs that could make a real difference, such as relatively cheap and consumer-responsive buses.

Still, taxpayers are on the hook for more than trolleys and trains. The five-year transportation bill Congress passed in 2005 contained funding for earmarks such as:

•$1.5 million for the Paul Bunyan trail in Oberstar’s home state.

•$1.2 million to the Henry Ford Museum’s Greenfield Village in Dearborn, Mich.

•$4 million for graffiti elimination in New York City.

Ironically, the total amount set aside in the 2005 package for earmarks, including many frivolous road and bridge ventures, is $24 billion … close to the $25 billion that the new gas tax will supposedly raise over the next three years.

Given all of the misdirected funds swirling about Washington and state capitals, wouldn’t it be wiser to shift this money toward priorities identified by structural engineers rather than self-interested politicians?

Some of the 2005 legislation’s loot hasn’t been spent yet, while other programs, such as subsidized ethanol car-fuel and the FreedomCAR research project, can be revisited too.

In addition, the gas tax is hardly an ideal mechanism for funding highways, but if policymakers are to continue portraying it that way, they should act the part.

Gasoline taxes should pay only for automobile-related infrastructure. Thinking ahead, Congress should enact Arizona Rep. Jeff Flake’s legislation to “devolve” most highway spending decisions – and taxes – to the states.

Although some states, such as California and Wisconsin, are no slouches in raiding road-tax collections, general assemblies and city councils are often more accountable to voters.

The private sector can also help, by being allowed to build High Occupancy Toll roads alongside existing interstates. With HOT, everyone wins: those willing to pay more for a faster trip can do so, thereby easing traffic on regular, tax-funded roadways.

Other government-owned assets could be operated through congestion charges on driving and parking that reflect supply and demand. Prudent user fees could work for hiking trails and museums as well.

The American Society of Civil Engineers estimates that fixing our structurally deficient bridges will cost more than $9 billion annually for 20 years. Since governments will collect more than 400 times this amount in revenues for 2007, bridge repairs can and should be funded without a tax hike.

Politicians need only rearrange budgets to focus on basic maintenance and traffic alleviation. Their constituents, the economy and the environment … not to mention their poll numbers … will be better off.