What Is a Road Bond: Types, Taxpayer Impact, and Investor Benefits

A road bond is a municipal bond that a state, county, or city issues to raise money up front for building, repairing, or expanding roads, highways, and bridges, then repays to investors over time with interest. Most road bonds mature anywhere from one to 30 years after issuance, and the interest investors earn is generally exempt from federal income tax under Section 103 of the Internal Revenue Code.¹ For taxpayers, bonds spread the cost of a large project over decades instead of forcing a sudden tax spike. For investors, they offer a relatively safe, tax-advantaged stream of income.

How a Road Bond Works

The mechanics are simple. A government identifies a road project it cannot pay for out of its annual budget. It issues bonds, which are essentially IOUs promising to repay the borrowed amount plus interest on a set schedule. Investors buy the bonds, the government uses the proceeds to pay for the work, and over the bond’s life the government makes regular interest payments, usually every six months. When the bond matures, the government returns the original principal.

Repayment schedules vary. Serial bonds spread repayment across a sequence of maturity dates, often with one group coming due each year for up to 20 years. Term bonds come due all at once after a longer period, commonly around 20 years. Many road bonds also include a call provision, which lets the government redeem the bonds early, typically after a waiting period of about 10 years. When a bond is called, the investor gets the principal back and sometimes a small premium, but the interest payments stop. Governments call bonds when interest rates drop, refinancing the debt at a lower rate the same way a homeowner refinances a mortgage.²

Types of Road Bonds

The type of road bond determines who bears the financial risk and where the repayment money comes from.

General Obligation Bonds

General obligation (GO) bonds are backed by the “full faith and credit” of the issuing government, which pledges its taxing power to repay investors. If a dedicated revenue source falls short, the government can draw on property taxes, sales taxes, or other general revenue.³ That broad backing makes GO bonds among the safest municipal investments. The trade-off is that taxpayers are ultimately on the hook, which is why many jurisdictions require voter approval before issuing them.⁴

Revenue Bonds

Revenue bonds are repaid only from income the project itself generates. A toll road bond is paid back from the tolls drivers pay to use that road. Other pledged sources might include dedicated fuel taxes, vehicle registration fees, or grants. If the pledged revenue comes up short, bondholders cannot force the government to raise taxes or tap other funds to make up the difference.⁴ Because repayment depends on a single stream rather than the government’s full taxing power, revenue bonds carry more risk than GO bonds and usually pay slightly higher interest to compensate.²

Private Activity Bonds

When a private company partners with a government agency to build or operate a road, private activity bonds (PABs) can come into play. These let a private project sponsor borrow at the lower, tax-exempt interest rates normally reserved for government debt. The U.S. Department of Transportation is authorized to allocate up to $30 billion in PABs for highway and surface transportation projects, a cap raised from $15 billion by the Infrastructure Investment and Jobs Act of 2021.⁵ Eligible projects generally must receive federal highway assistance under Title 23 of the U.S. Code.

What a Road Bond Means for Taxpayers

If you have ever seen a road bond measure on a ballot, it was almost certainly a GO bond. Because GO bonds put taxpayers’ money on the line, many state constitutions and local charters require voter approval before they can be issued. Revenue bonds typically do not require a public vote because they are repaid from project income rather than tax dollars.

When a bond measure appears on your ballot, four things matter: the total amount being borrowed, the estimated interest cost over the life of the bonds, the projects the money will fund, and the source of repayment. A $500 million bond issue might cost $750 million or more after interest, and the total is what taxpayers actually pay. Voting “yes” on a GO measure authorizes the government to use tax revenue to repay investors if the project or dedicated revenue stream falls short.⁶ Bond oversight committees and annual audits are common accountability mechanisms, though their existence and authority vary by jurisdiction.

What a Road Bond Means for Investors

The biggest draw is the federal tax break. Interest earned on state and local bonds is excluded from federal gross income under Section 103.¹ An investor in the 37 percent federal bracket keeps far more of the interest from a road bond than from a comparable corporate bond. Many states also exempt the interest from state income tax when the investor lives in the issuing state, though this varies.

There are exceptions. Private activity bonds that do not qualify under the Internal Revenue Code lose their tax-exempt status. Even for qualifying PABs, the interest may be subject to the alternative minimum tax, so higher-income investors should check AMT exposure before buying. Standard GO and revenue bonds issued directly by a government entity are not subject to AMT.

Road bonds are among the safer investments available, but safe does not mean risk-free. The SEC identifies credit risk, interest rate risk, call risk, inflation risk, and liquidity risk as the main concerns for all municipal bonds.⁷

Credit risk is the possibility the issuer fails to make interest or principal payments. Historically, municipal defaults are rare. From 1970 to 2022, the five-year cumulative default rate for all rated municipal bonds was 0.08 percent. General government bonds defaulted at just 0.03 percent over the same period. Revenue-backed “competitive enterprise” bonds, which include some toll road and transportation projects, had a higher five-year default rate of 0.35 percent, still a fraction of the corporate rate.

Interest rate risk cuts the other way: when market rates rise, the market value of existing bonds falls. If you need to sell before maturity, you could get back less than you paid. Call risk compounds the problem, because if rates drop, the government may redeem the bonds early and end your above-market interest payments sooner than planned.² Investors who hold investment-grade bonds to maturity face much less practical risk than those trading actively. Credit ratings from Moody’s, S&P, and Fitch provide a snapshot of credit risk at the time of rating. Ratings can change, and they are assessments of default likelihood, not guarantees.⁷

Federal Programs That Lower Borrowing Costs

Several federal programs make road bonds cheaper or more accessible for state and local governments, which indirectly reduces the share of each bond dollar that goes to interest instead of pavement. TIFIA, the Transportation Infrastructure Finance and Innovation Act program, provides direct federal credit assistance; each dollar of federal funds can support up to $10 in TIFIA credit assistance and leverage roughly $30 in total transportation investment. GARVEEs, or Grant Anticipation Revenue Vehicles, are bonds backed by a pledge of future federal highway funding, letting states borrow against money Congress has authorized but not yet distributed. State Infrastructure Banks are revolving loan funds capitalized with federal highway dollars that lend to state and local road projects, sometimes at below-market rates.⁸ The 2021 Infrastructure Investment and Jobs Act expanded several of these tools and raised the PAB cap.⁹

1
Office of the Law Revision Counsel. 26 USC 103 – Interest on State and Local Bonds
2
Municipal Securities Rulemaking Board. Municipal Bond Basics
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U.S. Securities and Exchange Commission. What Are Municipal Bonds
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Municipal Securities Rulemaking Board. Sources of Repayment
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U.S. Department of Transportation. Private Activity Bonds
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Investor.gov. Municipal Bonds
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U.S. Securities and Exchange Commission. Municipal Bonds – Understanding Credit Risks
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Federal Highway Administration. Federal Program Financing Tools
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U.S. Congress. HR 3684 – 117th Congress (2021-2022) – Infrastructure Investment and Jobs Act