Federal spending on transportation this year has reached near-record levels according to an analysis released last month by the Congressional Research Service (CRS). In fiscal 2018, outlays reached $86.1 billion, just shy of the $87.5 billion (using inflation-adjusted 2018 dollars) spent with a trillion-dollar stimulus package. In general, these funds are distributed to the states in the form of grants not just for roads and bridges, but also for rail, maritime, aviation and transit projects.

"Virtually all federal highway funding and most federal transit funding comes from the Highway Trust Fund, whose revenues come largely from the federal motor fuels excise tax," CRS transportation analyst David Randall Peterman wrote.

The highway trust fund will spend $54 billion in 2018. Various transportation special interest groups will point to the difference between that figure and the $41 billion in gas tax revenue as proof that motorists are not paying enough. They claim that this is happening because gas tax receipts are going down, but the numbers suggest that this is not the case. The Treasury Department's latest monthly income statement reported a 5.3 percent increase in federal highway trust fund receipts through July. Trust fund money comes from taxes on gasoline, diesel fuel and truck tires. The transportation funding "shortfall" comes from skimming motorist money to bankroll increasingly expensive, non-road related projects like bicycle paths, nature trails, transit and rail. In a 2004 report, the US DOT's Bureau of Transportation Statistics calculated the distribution of these subsidies (view report in 250k PDF file).

"Users of the highway passenger transportation system paid significantly greater amounts of money to the federal government than their allocated costs," the DOT report explained.

Motorists paid an extra $1.91 per thousand passenger-miles traveled in taxes to the federal government compared to passenger rail, which received a subsidy of $186.35 per thousand passenger-miles. Transit received a subsidy of $118.26. The figures covered 1990 to 2002.

The most up-to-date information from the Federal Highway Administration demonstrates that motorists are still paying more than their fair share at the local, state and federal level combined. In 2016, motorists paid $96.8 billion in federal and state gasoline taxes, $14.5 billion in tolls, $12.7 billion in vehicle-related property taxes and $20.7 billion in registration fees for a grand total of $183 billion when additional revenue from interest and bond issues is included. Out of this total, $106 billion was spent on capital outlay for federal, state and local roads and $49.7 billion on road maintenance with $19.7 billion spent on administrative and research expenses, for a grand total of $175.4 billion in road expenditures (view chart in 75k PDF file).

Overall federal spending on all categories of transportation is up significantly in 2018, CRS noted. The congressional analysts noted that the Transportation Department received an 11.8 percent jump -- $9.1 billion -- in spending authority over the previous year. President Trump tried to hold the line on spending by proposing a $75 billion transportation budget that would have zeroed out subsidies for toll roads and trolleys through the Tiger grant program while also slashing subsidies for Amtrak and transit grants. The US House and Senate used an omnibus spending bill to hike spending by $11 billion.

The biggest winner in the increased budget is rail, which will enjoy a 66 percent spending increase in 2018.