The first involves how to structure the decision-making process for highway projects. The report addresses the use of formulas to determine how and where funds for highway projects should be distributed.

"Although the current formulaic approaches to dividing federal resources for highways among the states may address notions of fairness or equity, the formulas do not necessarily provide federal support to the most economically advantageous projects," according to the report.

In examining alternative methods for selecting highway infrastructure projects, the report touches upon some examples that Congress has already either authorized or considered. These include the Transportation Infrastructure Finance and Innovation Act loan program whereby the U.S. Department of Transportation evaluates eligible projects based on such criteria as the extent to which they generate economic benefits, draw on private capital, and promote innovative technologies.

The report also highlights the Obama administration's proposed infrastructure bank as another possible option for deciding which projects should receive federal funding.

"The advantages and disadvantages of placing decision-making authority for highway infrastructure with an infrastructure bank would depend on the scope of its responsibilities and the specific design of its decisionmaking," CBO states.

Another key area for future concern for Congress involves how much money to spend on highway infrastructure. As the report outlines, the options to be considered include basing future spending on existing amounts, targeting measures of a highway's performance such as average traffic delay or pavement quality, and funding projects for which benefits would surpass the costs involved.

"Depending on the performance targets or threshold of benefits chosen, total spending could increase or decrease," the report suggests.

Another challenge that Congress will need to take up is how to pay for that spending. As the report highlights, the federal government's programs for highway infrastructure are financed primarily by various taxes on users that flow through the Highway Trust Fund. With the taxes currently in effect forecast to be insufficient to continue existing spending levels in future years, the report sets forth funding alternatives that Congress might wish to consider.

Those alternatives include charging drivers according to the costs of their use of the highway infrastructure (one example would be creating a mileage-based fee), stabilizing the Highway Trust Fund's purchasing power by indexing fuel taxes to account for inflation, and securing borrowed funds through private financing.

The eight-page report, "Spending and Funding for Highways," is available at bit.ly/CBO-Report.