As Americans cut back on driving, federal motor-fuels taxes and other revenue flowing into the Highway Trust Fund dropped by $3 billion in fiscal year 2008, compared with the sum collected the year before, the U.S. Dept. of Transpor­tation reports. DOT Secretary Mary Peters warns that if traffic continues downward, the trust fund may show a shortfall sooner than anticipated. Other observers share that worry.

DOT said on Nov. 19 that the trust fund took in $31 billion in fiscal 2008, down 8.8% from the $34 billion collected in 2007. As income fell,  spending from the trust fund on highway and transit projects rose by $2 billion, compared with 2007’s level.

Vehicle miles traveled continued to dip in September, declining 4.4% from September 2007, the Federal Highway Administration reports. That marks the eleventh consecutive month vehicle miles were down from year-earlier levels.

The falloff in highway travel and the resulting drop in trust-fund income threatened to push the trust fund’s highway ac­count into a deficit by Sept. 30. About two weeks before that date, a crisis was averted when President Bush signed a bill shifting $8 billion to the trust fund from the general fund.

Even with the infusion, the highway ac­count may not stay in the black through fiscal 2009, some fear. “I think that that is a very real possibility,” says Greg Cohen, American Highway Users Alliance president. “Clea­r­ly we need a more sustainable solution, including a user-fee increase.” Peters has opposed boosting the gasoline tax, but Cohen says a hike will “have to be part of the mix,” at least as an option to be discussed.