One year after the Minneapolis bridge collapse sent a jarring wake-up call about the nation’s crumbling infrastructure, little work is being done to repair bridges and roads amid a funding crisis that threatens more delays and risks to the public, federal and local authorities acknowledge.

The problem deepens each month because of shrinking gas tax revenues that are needed to shore up ailing bridges. People are driving less and many have shifted to more fuel-efficient vehicles to cope with record prices at the pump, another factor contributing to the freefall in gas-tax collections.

The outlook is not encouraging:

The federal Highway Trust Fund, which uses gas-tax collections to pay for a large chunk of road and mass-transit projects, is expected to go from an $8 billion balance at the beginning of the current fiscal year to a deficit of $3.1 billion sometime in the next fiscal year, which starts in October.

Miles traveled on U.S. roads have declined in nine of the last 12 months, according to the U.S. Department of Transportation. The government warns it may not be able to meet earlier pledges to help states pay for highway projects already started, although the House last week passed emergency legislation that would provide $8 billion in general revenues to the highway fund.

Road expansion projects to address worsening traffic congestion have been mostly stripped from the Illinois highway program through 2014. The state has gone four years without renewing its capital construction funding program.

Traffic congestion is already choking cities from Los Angeles to Chicago to New York. Yet today’s congestion would seem like a mere inconvenience compared to the gridlock crisis expected in the future as more cars and trucks hit the roads.

States are losing additional ground because of escalating costs for asphalt, steel and other construction materials. Steel prices have skyrocketed 93 percent in the past year, according to the American Road & Transportation Builders Association.

Meanwhile, the Bush administration is staunchly opposing the first effort in Congress, tied to the first anniversary of the I-35W bridge collapse in Minneapolis, to increase spending to repair and replace the most dangerous bridges in the U.S. The proposed $1 billion national bridge program, sponsored by U.S. Rep. Jim Oberstar, D-Minn., passed the House last week. The Senate is expected to take up the House highway and bridge bills soon.

Thirteen people died when their vehicles plunged into the Mississippi River last Aug. 1 after the I-35W bridge broke apart. A design flaw and improper loading of road-resurfacing equipment on the bridge are tentatively blamed for the tragedy, according to investigators.

U.S. Transportation Secretary Mary Peters, who was in Chicago Thursday, said the $1 billion Oberstar legislation “rewards states that haven’t invested in their bridges and penalizes states that have.”

In a meeting with the Tribune Editorial Board, Peters called the plan “perverse,” adding that no funding source has been identified.

About 152,000 U.S. bridges are either structurally deficient or functionally obsolete, according to the Federal Highway Administration, which says one of four bridges is in disrepair.

It would cost $140 billion to repair all the bridges, according to the American Association of State Highway and Transportation Officials.