What Is a Road Bond: Types, Repayment, and Investor Risks

A road bond is a municipal bond that a state, county, or city issues to raise money upfront for building, repairing, or expanding roads, highways, and bridges. Instead of waiting years to accumulate tax revenue, the government borrows from investors and repays them, with interest, on a set schedule. Most road bonds mature between one and 30 years after issuance, and the interest investors earn is generally exempt from federal income tax. For taxpayers, this spreads the cost of large projects over time; for investors, it offers a relatively safe, tax-advantaged income stream.

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. Investors buy the bonds, the government uses the proceeds to fund construction, and interest payments go out on a regular schedule, usually every six months. When the bond matures, the government returns the original principal.¹

The repayment structure varies. Serial bonds spread repayment across a series 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 include a call provision, which lets the government redeem them early, usually after a waiting period of about 10 years. Governments typically call bonds when interest rates fall so they can refinance at a lower rate, similar to how a homeowner refinances a mortgage. If a bond is called, the investor gets the principal back (sometimes with a small premium) but stops receiving interest.¹

The Main Types of Road Bonds

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

General Obligation Bonds

General obligation (GO) bonds are backed by the “full faith and credit” of the issuing government, meaning the government pledges its taxing power to repay investors. If dedicated revenue sources like tolls or gas taxes fall short, the government can draw on property taxes, sales taxes, or other general revenue to cover payments.² That broad backing makes GO bonds among the safest municipal investments. Because taxpayers are ultimately on the hook, many jurisdictions require voter approval before issuing them.³

Revenue Bonds

Revenue bonds are repaid only from income the road project itself generates. A toll road bond gets paid back from tolls. Other pledged sources might include dedicated fuel taxes, vehicle registration fees, or grants. If that revenue falls short, bondholders cannot force the government to raise taxes to make up the difference.³ 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 rates in exchange.¹

Private Activity Bonds

When a private company partners with a government agency to build or operate a road under a public-private partnership, private activity bonds (PABs) can enter the picture. These let a private sponsor borrow at the lower interest rates normally reserved for tax-exempt 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 2021.⁴ Eligible projects generally must receive federal highway assistance under Title 23 of the U.S. Code.

How Road Bonds Get Repaid

Repayment depends entirely on the bond type, and the distinction matters for both investors and taxpayers.

GO bonds draw on the government’s general tax base. Property taxes are the most common backstop, but sales and income taxes can also contribute. When you vote yes on a GO bond measure, you are authorizing the government to use tax revenue to repay investors if needed.⁵

Revenue bonds work differently. Repayment is limited to whatever income stream the bond agreement pledges. For a toll road, that means toll receipts. For a highway funded by a dedicated gas tax, it means that specific tax. Bondholders cannot compel the government to tap other funds if the pledged revenue falls short.³ Revenue bonds insulate the general public from repayment obligations but expose investors to more uncertainty.

Tax Treatment for Investors

One of the biggest draws of road bonds is the federal tax break. Under Section 103 of the Internal Revenue Code, interest earned on state and local bonds is excluded from federal gross income.⁶ An investor in a high 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.⁶ 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.

Risks to Weigh

Road bonds sit among the safer investments available, but safe does not mean risk-free. The SEC identifies several risks that apply to all municipal bonds, including credit risk, interest rate risk, call risk, inflation risk, and liquidity risk.⁷

Credit risk is the possibility that the issuer fails to make interest or principal payments. Historically, municipal defaults are rare compared to corporate bonds. 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 default rate.

Interest rate risk runs the opposite direction from what most people expect: when market interest rates rise, the value of existing bonds falls. Selling a road bond before maturity can mean getting back less than you paid. Call risk compounds this. If rates drop, the government may redeem the bonds early, returning your principal but ending your above-market interest payments sooner than expected.¹ Investors who plan to hold until maturity and stick with investment-grade issues face much less practical risk than active traders.

Credit ratings from Moody’s, S&P, and Fitch offer a snapshot of default risk at the time of rating. Ratings can change over the life of a bond, and they are assessments of likelihood, not guarantees.⁷

When Voters Get a Say

A road bond measure on a ballot is almost always a GO bond. Because GO bonds put taxpayer 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, since they are repaid from project income rather than tax dollars.

When a road bond measure appears on your ballot, look at the total amount being borrowed, the estimated interest cost over the life of the bonds, the projects the money will fund, and how repayment will work. A $500 million bond issue can cost $750 million or more after interest, and that total is what taxpayers ultimately pay. Bond oversight committees and annual audits are common accountability mechanisms, though their existence and authority vary by jurisdiction.

1
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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Office of the Law Revision Counsel. 26 USC 103 – Interest on State and Local Bonds
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U.S. Securities and Exchange Commission. Municipal Bonds – Understanding Credit Risks