Introduction

The United States has approximately 620,000 bridges longer than 20 feet on public roads. The number of bridges classified as poor has declined gradually for many years, but as of June 2021, about 44,000 remain. Most of these bridges are owned and maintained by state and local governments. The federal government has established bridge inspection standards and provides funding to support the rehabilitation and replacement of existing bridges and the construction of new bridges.

The passage of the Infrastructure Investment and Jobs Act (IIJA; P.L. 117-58), covering the years FY2022-FY2026, initiated a major change in congressional bridge funding policy. Prior to passage, federal bridge funding came from programmatic sources that could be spent on either roads or bridges in accordance with priorities set by the states. The IIJA authorized $43.3 billion over five years exclusively for bridge projects; increased authorizations for formula grants that states may choose to use for bridges; and expanded funding for discretionary programs under which bridge projects are eligible.

This report examines current bridge characteristics and conditions, national funding needs, and the implications of the attempt in the IIJA to speed up the pace of bridge improvements. It concludes with a discussion of issues that may be of congressional concern, including the potential impact of inflation on future bridge spending, the future of toll-funded bridges, and spending on bridges not on the federal-aid system.

Bridge Characteristics

Of the 620,000 bridges on public roads, about 48% are owned by state governments, and 50% are owned by local governments. State governments generally own the larger and more heavily traveled bridges, such as those on the Interstate Highway system. Less than 2% of highway bridges are owned by the federal government, primarily those on federally owned land.¹

About 9% of all bridges carry Interstate Highways, and another 14% serve principal arterial highways other than Interstates.² Interstate and other principal arterial bridges carry about 80% of average daily bridge traffic. The highest traffic loads are on Interstate Highway bridges in urban areas; these accounted for only 5% of all bridges but carried 37% of average daily bridge traffic in 2021.³

Bridge Inspection

Under the National Bridge Inspection Program, all bridges longer than 20 feet on public roads must be inspected by qualified inspectors, based on federally defined requirements (23 U.S.C. §144). Federal agencies are subject to the same requirements for federally owned bridges, such as those on federal lands. Data from these inspections are reported to the Federal Highway Administration (FHWA), which uses them to compile a list of bridges in poor condition. States may use this information to identify which bridges need replacement or repair.⁴

FHWA oversees bridge inspection through the National Bridge Inspection Standards (NBIS).⁵ The NBIS set forth how, with what frequency, and by whom bridge inspection is to be completed. The standards provide the following:

• Each state is responsible for the inspection of all public highway bridges within the state except for those owned by the federal government or Indian tribes. Although the state may delegate some bridge inspection responsibilities to smaller units of government, the responsibility for having the inspections done in conformance with federal requirements remains with the state.
• Inspections can be done by anyone qualified under the standards for qualification and training. The inspectors may be state employees, consultants to the states, or others.
• Inspection of a federally owned bridge is the responsibility of the federal agency that owns the bridge.
• In general, a bridge must be inspected at least every 24 months. States are to identify bridges that require less than a 24-month interval. States can also request FHWA approval to inspect certain bridges at intervals as long as 48 months. The interval for an underwater inspection is generally 60 months but may be increased to 72 months with FHWA permission. Nonredundant steel tension members must undergo a hands-on inspection at intervals not to exceed 48 months.⁶
• An on-site inspection team must have a leader who meets additional training requirements. Damage and special inspections do not require the presence of a team leader.
• Load rating of a bridge must be under the responsibility of a registered professional engineer. Structures that cannot carry maximum legal loads for the roadway must be posted.

The vast majority of inspections are performed under state authority. FHWA bridge engineers, at times, perform field reviews to assure that states are complying with the bridge inspection requirements. FHWA also provides on-site engineering expertise in the examination of the causes of catastrophic bridge failures.

Bridge Conditions

Bridge condition data reported to FHWA are collected in the National Bridge Inventory. This information permits FHWA to characterize the existing condition of bridges as good, fair, or poor. A bridge is considered in good condition if the deck, superstructure, and substructure are rated at least 7 on a 0-9 scale. If any of these bridge elements is rated 5 or 6, a bridge is considered in fair condition. A bridge is considered in poor condition if any element is rated 4 or less. A bridge classified as poor is not necessarily unsafe but may require the posting of a vehicle weight restriction. When officials determine that a bridge is unsafe, it is closed to traffic. In 2021, about 3,500 (0.5%) bridges were closed and another 62,000 (10%) had a weight restriction.

In 2021, 278,000 public road bridges (45%) were considered good, 298,000 (48%) fair, and 44,000 (7%) poor. The number of poor bridges declined by about 13,000 over the 10-year period from 2012 to 2021, whereas the number of bridges in good condition dropped by 9,000, and the number of bridges in fair condition increased by 35,000 (Table 1).

About 80% of the bridges in poor condition in 2021 were located in rural areas. Nevertheless, urban bridges in poor condition are generally much larger and carry more traffic than those in rural areas and, therefore, are more expensive to fix. In 2021, 58% of the total deck area of bridges in poor condition was in urban areas. The amount of deck area in poor condition has dropped by about the same proportion in urban and rural areas from 2012 through 2021, nearly 30%.

Figure 1. Urban and Rural Highway Bridges in Poor Condition, 2012-2021

Source: Bureau of Transportation Statistics, National Transportation Statistics, Table 1-28, at https://www.bts.gov/content/condition-us-highway-bridges. Notes: Data for 2012-2020 are as of December 31. Data for 2021 are as of June 15.

Bridges on Interstate Highways are generally in better condition than those on more lightly traveled routes: 3% of urban Interstate Highway bridges were considered poor in 2021, whereas 7% of urban bridges on local roads were classified as poor.⁷ Likewise, 3% of rural Interstate Highway bridges were poor in 2019, compared with 11% of rural bridges on local roads. In 2021, 9% of bridges owned by local governments were classified as poor, compared with 5% of state-owned bridges. For bridge condition ratings by state and territory, see Table A-1.

Bridge Infrastructure Funding

Federal and State Roles

Federal bridge funding shares the basic attributes of federal aid to highways, which is administered by FHWA.⁸ Most of this funding is apportioned by formula to the states from the Highway Trust Fund and is not subject to annual appropriation by Congress. Each state's funds are divided among 10 so-called core formula programs established by law. State departments of transportation (state DOTs) are free to spend the funds allocated to each program in any way consistent with that program's purposes, so long as they comply with detailed federal planning guidelines and performance management measures.⁹ State DOTs execute the contracts and oversee the construction process. The decision about how much of a state's formula funding to spend on bridges rather than roads is generally up to the state DOT.¹⁰ States are allowed to transfer ("flex") up to 50% of each core formula program's apportioned funds to other formula programs.¹¹ Most bridge projects receive a federal cost share of up to 80%, but for bridges on Interstate Highways, the share is generally up to 90%. The use of federal funds for bridges, unlike most road funding, is not restricted to designated federal-aid highways and may be used on any bridge listed in the National Bridge Inventory.

In addition, states or municipalities may seek discretionary (competitive) grants awarded by FHWA or the Office of the Secretary of Transportation. For example, the Nationally Significant Freight and Highway Projects Program (renamed INFRA) also may award funding for large bridge projects.¹²

Congress and Bridge Policy

For the first 53 years of federal aid to highways, federal policy left decisions about allocating money to bridge projects to the states. There was no federal program funding dedicated to bridges. This changed following the collapse of the so-called Silver Bridge over the Ohio River in December 1967, which resulted in the deaths of 46 people. Congress required the Secretary of Transportation to establish the NBIS in 1968. In February 1970, FHWA reported that of the 563,000 bridges in the United States, 88,900 were "critically deficient." Despite the findings, the agency recommended against funding a "special bridge program" on the grounds that such a program would "necessarily be at the expense of other urgent highway needs."¹³

Contrary to this recommendation, the Federal-Aid Highway Act of 1970 (P.L. 95-599) authorized the discretionary Special Bridge Replacement Program, the first stand-alone federal highway bridge funding program. Having a stand-alone program was a way for Congress to dedicate certain funding to bridges rather than roads. The Surface Transportation Assistance Act of 1978 (P.L. 95-599) replaced this with a new formula-based Highway Bridge Replacement and Rehabilitation Program, which expanded eligibilities to include bridge rehabilitation and projects on off-system bridges. Roughly 20% of the program's funding was set aside for a bridge discretionary program for large bridge projects. These discretionary funds were under the control of FHWA.

The 1991 Intermodal Surface Transportation Efficiency Act (P.L. 102-240) allowed a state to transfer 40% of its bridge apportionment to other highway programs (the percentage was increased to 50% in 1998). The Moving Ahead for Progress in the 21^st Century Act (MAP-21; P.L. 112-141), enacted in 2012, allowed the dedicated bridge program—then called the Highway Bridge Program—to expire at the end of FY2012, largely returning the decision to the states on how much of their federal formula grants to spend on bridges. This situation persisted until Congress passed the IIJA, which reasserted bridge spending as a congressional priority.

Recent Spending History, FY2015-FY2021

Under the Fixing America's Surface Transportation Act (FAST Act; P.L. 114-94), as amended through FY2021, bridge projects were funded from highway programs that states or grantees could also use to fund road projects. States also had access to residual funds from the expired Highway Bridge Program. Table 2 shows the total obligation of federal funding for bridges, including funds from the former Highway Bridge Program and those from all other programmatic sources, from FY2015 through FY2021. The table also expresses obligations in constant FY2015 dollars to show the impact of inflation.

During FY2021, obligations for spending on bridges were approximately 26% higher than in FY2015. When adjusted for inflation in road construction costs, however, the increase was about 8% during these years.

Additional Appropriated Funds

Beginning in FY2018, Congress has appropriated funding for bridges outside the authorization process. The Consolidated Appropriations Act, 2018 (P.L. 115-141) included $225 million for a competitive bridge program for states with a population density of 100 per square mile or less. The Consolidated Appropriations Act, 2019 (P.L. 116-6) provided $475 million for a Bridge Replacement and Rehabilitation Program, to be distributed by formula to states for which the percentage of total bridge deck area classified as poor was at least 7.5%. The Further Consolidated Appropriations Act, 2020 (P.L. 116-94) provided $1.15 billion but broadened the eligibility to states for which the percentage of total bridge deck area classified as poor is at least 5%. The Consolidated Appropriations Act, 2021 (P.L. 116-260) provided $1.08 billion for this program. For these years, Congress in effect pursued a two-pronged approach by making bridges eligible for funding at state discretion under the large highway formula programs established in authorization acts and supplementing these funds with targeted bridge funding in annual appropriations acts.

Bridge Funding and Policy Changes in the IIJA

The IIJA both reauthorized spending authority from the Highway Trust Fund for highway programs at an increased level and provided an additional boost to infrastructure spending via multiyear supplemental appropriations from the Treasury general fund. Some programs are authorized to receive additional funding subject to appropriation in future annual appropriations acts.

New Bridge Programs

The IIJA created two stand-alone programs dedicated to bridge projects:

• The Bridge Replacement, Rehabilitation, Preservation, Protection, and Construction Program, generally referred to as the Bridge Formula Program (BFP), is to distribute $5.5 billion annually to the states through FY2026.
• The Bridge Investment Program (BIP) is authorized to distribute nearly $16 billion in competitive grants through FY2026, although $3.265 billion of that amount is subject to future appropriations (see Table 3).

If the states continue to spend on bridges from their ongoing federal programs at the FY2021 level, these new IIJA programs would roughly double average annual spending (unadjusted for inflation) on highway bridges. Adjusting these amounts for expected inflation using the Congressional Budget Office (CBO) gross domestic product (GDP) price index for FY2017-FY2032 indicates a substantial loss of purchasing power over the life of the IIJA. However, most of the increase in new federal bridge spending remains.

Bridge Formula Program

BFP funds are distributed to states (including the District of Columbia and Puerto Rico) based on each state's cost to replace its poor-condition bridges and to rehabilitate its fair-condition bridges, relative to the total nationwide cost.¹⁴ The IIJA funds the program with $5.5 billion annually over the life of the act. The minimum amount a state will receive is $45 million annually. At least 15% of each state's funds must be spent on bridges not on the federal-aid system, so-called "off-system bridges," and $165 million (3%) is set aside annually for bridges on tribal lands.¹⁵ Off-system bridges, owned by sub-state government entities or federally recognized tribes, are eligible for 100% federal share. State DOTs choose the projects, other than for tribal lands bridges. The funds may be used for highway bridge replacement, rehabilitation, preservation, protection, or construction projects on any bridge listed in the National Bridge Inventory or any new highway bridge that upon completion would be included in the inventory. BFP funds may not be transferred to other programs. This formula program is entirely funded with multiyear appropriations from the general fund.

Bridge Investment Program

The BIP provides competitive grants for bridge replacement, rehabilitation, preservation, or resiliency improvements for bridges on the National Bridge Inventory.¹⁶ The IIJA authorizes an average annual $3.153 billion for the program, of which roughly one-fifth is subject to annual appropriations. A state or group of states, sub-state governmental entities or groups of such entities, special purpose districts or public authorities that serve a transportation function, metropolitan planning organizations that serve populations over 200,000, federal land management agencies, tribal governments, or any combination of the aforementioned entities may apply directly to the U.S. Department of Transportation.¹⁷ BIP grants can be used to replace, rehabilitate, preserve, or protect (including adding resilience features) bridges or to replace or rehabilitate culverts to improve flood control and habitat connectivity for aquatic species. A grantee may also use BIP funding to pay subsidy costs of a federal loan under the Transportation Infrastructure Finance and Innovation Act (TIFIA).

The program creates three categories of projects for which eligible entities may apply:

• $20 million is set aside annually for planning, feasibility analysis, and revenue forecasting grants. There is no minimum size for planning grants.
• Large Bridge Project grants are available for projects with total eligible costs of greater than $100 million. The maximum award may not exceed 50% of the total eligible project cost, making the minimum award amount $50 million. The award may be split into a multiyear award over four consecutive fiscal years.
• Bridge Project grants are available for projects with total eligible costs of $100 million or less. The maximum award may not exceed 80% of the total eligible project cost, and the minimum award is $2.5 million.

The IIJA allows up to 5% of BIP funding to be used for eligible projects that consist solely of culvert replacement or rehabilitation of bridge-sized culverts (as defined under 23 C.F.R. §650.305) for flood control or to improve habitat connectivity for aquatic species.

Other sources of federal assistance may be used to satisfy the nonfederal share as long as the total federal share does not exceed the amount allowable under 23 U.S.C. §120 or 23 U.S.C. §124 for off-system bridges. For a federal land management agency, tribal government, or a consortium of tribal governments, federal funds made available under non-BIP federal programs (including Tribal Transportation Program and Federal Lands Transportation Program funds) may be used to pay the remaining cost of a BIP project.

Federal Lands and Tribal Bridges

Most funding for highways and bridges owned by the federal government or by Indian tribes does not come from the regularly apportioned programs discussed above. Funding is authorized separately, primarily from two stand-alone programs: the Tribal Transportation Program and the Federal Lands Transportation Program.¹⁸ The Tribal Transportation Program funds are under the control of the tribes, in cooperation with the Department of the Interior and the Department of Transportation. The Federal Lands Transportation Program funds are under the control of the federal land management agencies, with assistance and oversight from the Department of Transportation. A third program, the Federal Lands Access Program, funds facilities that provide access to federal lands. The use of these funds in each state is determined by a state committee that includes representatives of FHWA, the state DOT, and a political subdivision of the state.

Compared with the core highway formula programs, these programs are small. The IIJA provides $602 million annually for the Tribal Transportation Program and $439 million annually for the Federal Lands Transportation Program. The Federal Lands funding amount is divided among the National Park Service ($346 million), the Fish and Wildlife Service ($36 million), the U.S. Forest Service ($26 million), and other federal land management agencies ($31 million). The IIJA provides $298 million annually for the Federal Lands Access Program. These three programs' funds must cover road and bridge needs, and the funds may be used on public transportation projects. These programs are paid for from the Highway Trust Fund.

The IIJA also provides $205 million per year specifically for tribal bridges with funding set aside from the larger bridge programs, a sizable increase for tribal bridges annually under prior law, and $55 million annually under the National Significant Federal Lands and Tribal Projects Program. The IIJA created several new discretionary highway and bridge grant programs for which tribal projects are eligible.

Other Program Sources of Bridge Funding¹⁹

Broad sources of highway funding for states to improve their bridges existed prior to the IIJA and have been continued at increased funding levels. In particular, three of these formula programs—the Surface Transportation Block Grant Program, the National Highway Performance Program, and the National Highway Freight Program—together have been the major sources of bridge funding since FY2013 and continue to be available for bridge projects. Funding from other legacy formula programs, such as Transportation Alternatives and the Congestion Mitigation and Air Quality Improvement Program, also can be used, depending on the specifics of the project. According to FHWA data, in FY2021, $8.6 billion was obligated for bridge projects from all federal highway program sources (see Table 2). Competitive grant program grants (e.g., from INFRA) and the Local and Regional Project Assistance Program (also referred to as RAISE grants) continue to be available for bridge projects. Appalachian Development Highway System appropriations provided in the IIJA and annual appropriations bills may be used for bridge projects on that system.

FHWA's Emergency Relief Program

The Emergency Relief Program provides funding for bridges damaged in natural disasters or that are subject to catastrophic failures from an outside source.²⁰ The program provides funds for emergency repairs to restore essential travel immediately after the failure to restore essential traffic, as well as for longer-term permanent repairs.

The IIJA changed the time frame within which the federal government will pay 100% of the cost of emergency repairs from 180 days to 270 days from the date of the disaster. Later repairs, as well as permanent repairs, such as reconstruction or replacement of a collapsed bridge, are reimbursed at the same federal share that would normally apply to the federal-aid highway facility. The IIJA strengthens the language permitting the funding of added protective features to include features that are economically justifiable improvements that will mitigate the risk of recurring damage from extreme weather, flooding, and other natural disasters. The act also adds a list of eligible protective features under the program.

New Non-bridge Programs That Can Assist Bridge Projects

The IIJA created new formula and competitive grant programs that, while not stand-alone bridge programs, can provide funding for bridge projects, depending on the specifics of the project. Among these programs are the following:

• Promoting Resilient Operations for Transformative, Efficient, and Cost-saving Transportation (PROTECT) funds can be used for bridge-related infrastructure resilience spending. The IIJA funds this new core formula program at an annual average of $1.46 billion. The act also created a PROTECT competitive grant program funded at an annual average of $300 million.
• Rural Surface Transportation Grant Program is funded at an annual average of $400 million.
• Nationally Significant Projects Program (also referred to as MEGA) is a multimodal program designed to fund large, complex transportation infrastructure projects, including highway bridges. The program is funded at $1 billion annually from multiyear appropriations and authorized to receive an additional $2 billion annually, subject to appropriation. The program is administered by the Office of the Secretary of Transportation.
• National Culvert Removal, Replacement, and Restoration Grant Program is a multimodal program to be administered by the Office of the Secretary that funds projects that improve or restore passage of anadromous fish (such as salmon). The program is funded at an annual average of $200 million in multiyear appropriations and authorized at $800 million annually, subject to appropriations.

Future Bridge Funding Needs

Every two years or so, FHWA assesses the condition and performance of the nation's highways and bridges, documents current spending by all levels of government, and estimates future spending needs to maintain or improve current conditions and performance.²¹ As with any attempt to forecast future conditions, a host of simplifying assumptions, omissions, and data problems influence these estimates. Among other things, the estimates rely on forecasts of travel demand. Despite such uncertainties and assumptions, these estimates provide a way to assess the level of current spending compared with what would be needed in the future under different scenarios. Because of the modeling involved, FHWA's future needs estimates for bridges are limited to fixing deficiencies in existing bridges only when the benefits outweigh the costs.

The most recent assessment was published in 2021 based on 2016 data. Represented in 2021 dollars, this assessment showed that $17.2 billion was spent on bridge rehabilitation or replacement by governments at all levels in 2016. An additional $1.9 billion was spent on the construction of new bridges.²² It estimated that fixing all bridge deficiencies existing in 2016 would cost $148 billion (in 2021 dollars). This figure is almost nine times the level of spending on bridge rehabilitation and replacement in 2016.²³

Of course, fixing all deficient bridges overnight is not feasible. FHWA, therefore, estimated how this investment backlog may change at various levels of spending during 2017-2036, taking into account the deterioration of existing bridges over that period. The results of this analysis are seen in Figure 2. FHWA estimated that eliminating the backlog by 2036 would require an investment of $28.1 billion annually (in 2021 dollars).

The IIJA provided an increase in federal highway funding overall and created new dedicated bridge funding programs that provide an annual average of $7.8 billion (in 2021 dollars) (Table 3). If states decide to commit the same amount of their general federal highway funding to bridges as they did in FY2021, about $8.6 billion, total federal funding committed to bridges would be about $16.4 billion annually. Assuming that state and local funds continue to provide 53% of all bridge spending, as has been the case in recent years, total bridge spending could amount to around $34.8 billion per year (in 2021 dollars) under the IIJA.²⁴

This bridge spending estimate does not take into account the increase in funding for general highway programs in the IIJA or the improved opportunity for accessing competitive grant programs for bridge projects. Even so, the funding amounts in the IIJA could conceivably allow for total spending for five years at the level FHWA estimates would be needed to eliminate bridge deficiencies if continued over 20 years (i.e., $28.1 billion per year), and have $6.7 billion per year available for the construction of new bridges. However, as state and local governments make most of the decisions concerning which projects to pursue and, within the limits of federal matching share requirements, how much of their own money to commit, it is uncertain whether total bridge spending will achieve this level.

Figure 2. Estimated Effect of Various Spending Levels on Bridge Investment Backlog (Average annual spending for 20 years)

Source: U.S. Department of Transportation, FHWA, and Federal Transit Administration, Status of the Nation's Highways, Bridges, and Transit: Conditions and Performance Report to Congress, 24th ed., October 2021, exhibit 10-15. Notes: The current funding level is for 2016, and the 20-year spending scenarios are for 2017 through 2036. CRS adjusted the data expressed in 2016 dollars to 2021 dollars using the implicit GDP deflator.

Issues for Congress

The IIJA replaced the former policy of gradual improvement of the nation's bridges with a more ambitious program to speed up the pace of bridge improvements. The implementation of this policy and its success in improving bridge conditions are likely to be of ongoing concern to Congress.

Loss of Purchasing Power

Because inflation was low for many years, it was not an issue during the reauthorization debate that preceded passage of the IIJA. However, more rapid price rises since early 2020 have raised the prospect that inflation may erode the value of the increased bridge spending provided in the IIJA. Inflation projections by CBO suggest that the funds authorized and appropriated in the IIJA could lose 10% of their purchasing power over the period FY2022-FY2026. ²⁵

The loss of purchasing power could be greater than this, given that indexes of highway construction costs have risen faster over the last five years than the measure used by CBO.²⁶

Another factor that could make the impact of inflation more severe is the way funding for highways is distributed and managed. Each year's federal highway funds are made available for obligation for four years. Obligation occurs when the state or grantee signs a project agreement with FHWA in which FHWA commits to the federal portion of the project cost. According to FHWA, 84% of funds are spent within three years of obligation, but some funds take as long as nine years to expend.²⁷ The time involved in expending authorized funds could make the loss in purchasing power greater than indicated in Table 3.

Programmatic Substitution

Given the large increase in bridge spending from bridge-only programs, states may choose to rely mainly on BFP and BIP to fund bridge projects and use a greater share of their core formula funds on non-bridge highway projects. This could result in the net increase in spending on bridges being less than Congress may have assumed in enacting the IIJA.

Maintenance of Effort

Research by CBO has estimated that state and local governments that receive federal grants for highway projects "reduce their own per capita spending on highway capital by 26 cents for an additional dollar of annual federal formula grants."²⁸ This raises the possibility that the IIJA will lead to less combined state and federal spending on highway bridges than previous state and local spending patterns imply.

Tolling of Non-tolled Bridges

Wider use of tolling could allow for more rapid improvement of major bridges. Heavily traveled bridges can be attractive targets for conversion to toll facilities—many bridges have no convenient alternatives, so drivers may find it difficult to avoid paying whatever toll is imposed. The revenue stream provided by tolls can make bridge building and reconstruction an attractive investment for private entities that are interested in participating in a public-private partnership. Tolling can also help projects become eligible for a TIFIA loan that requires a dedicated revenue stream for repayment.²⁹ Currently, any toll-free federal-aid highway bridge may be converted to tolling and receive federal highway aid if the conversion is related to the reconstruction or replacement of the bridge. Also, new bridges may be tolled.³⁰

The large increase in IIJA bridge funding could on the one hand lessen the use of tolling as a financing option, given that bridge tolls are often unpopular. On the other hand, the IIJA provides $50 million annually to the Congestion Relief Program for congestion solutions, including the imposition of tolls for congestion pricing. Congress may want to explore whether the IIJA has affected the use of tolls to fund construction or reconstruction of bridges.

Spending on Off-System Bridges

Historically, nearly all federal highway funding was restricted to roads and bridges on the federal-aid highway system. Highway bridges have been the main exception to the rule. A minimum level of spending on off-system bridges, which typically carry much less traffic than bridges on the federal-aid system, has been required in every highway authorization bill since 1978.

Congress's interest in funding off-system bridges was affirmed under the IIJA. The existing off-system bridge spending requirements were continued and the set-aside for off-system projects has been strongly supported by predominantly rural states and by many county and municipal governments. The policy could be an issue if it constrains resources available to repair or replace more heavily traveled bridges on major roads.

Appendix.