Federal lawmakers, the report says, would have to cut transportation spending by 92 percent or raise the gas tax by more than 50 percent in order to bring revenue and spending in line.
The Highway Trust Fund, which gets its money from taxes on gasoline and motor fuels, is the source of money for federal spending on highways, bridges, roads and transit. The fund has struggled for years to remain in the black -- ever since federal transportation spending started exceeding the dedicated taxes used to pay for it.
As Americans continue to drive less, and fuel efficiency continues to improve, the gas tax -- currently at 18.4 cents per gallon -- will be a financially unsustainable way of paying for transportation infrastructure going forward, many academics say.
Since it hasn't been raised in 20 years, the gas tax's purchasing power has dramatically declined. (It would be about 29 cents per gallon today if it had been indexed to inflation, according to the CBO.) While academics and transportation advocates almost universally agree with the idea of either increasing the gas tax or developing other fees to generate more reliable transportation revenue, neither of those ideas have gained traction in Congress.
The surface transportation bill, MAP-21, expires at the end of the 2014 fiscal year. The CBO writes that bringing the trust fund into balance after that would require cutting federal transportation spending from $51 billion to $4 billion, raising the gas tax by 10 cents or some combination of the two.
Another option -- one that's became Congress's favorite as of late -- would be to bail out the fund with general fund revenue. Indeed, when Congress passed last year's highway bill it neither increased revenue nor made cuts. Instead, it used general fund offsets to maintain transportation spending levels.
"There is no painless way out of the dilemma facing the [Highway Trust Fund] in coming years," Bob Poole, director of transportation policy at the Reason Foundation, said in a statement. "There seems to be very little political support for increasing federal fuel taxes, and no other source of new revenue is on the horizon."
Indeed, since 2008, Congress has transferred $41 billion to the trust to keep it afloat, with another $12.6 billion authorized for 2014. Another $14 billion transfer would be needed to prevent the projected shortfall in 2015, the CBO writes.
