A Fair rating means the weakest of the bridge's three main components (deck, superstructure, substructure) scores 5 or 6 on the FHWA's 0 to 9 scale. It is one or two grades above the Poor threshold. These bridges receive no federal replacement priority and they are typically inspected once every 24 months. The number of Fair bridges is not a safety emergency, but these structures represent a wasted opportunity for money-saving investments that could reduce future repair spending.

The meaning of "Fair"

A bridge's condition classification is determined by its weakest component. When inspectors rate the deck, the superstructure, and the substructure on a 0 to 9 scale, the FHWA classification takes the lowest of those three numbers. When the lowest rating out of the three is 7 or above, the final condition is classified as Good. A lowest rating of 4 or below is Poor, and a 5 or a 6 is Fair.

So a Fair bridge is one whose weakest component, deck, superstructure, or substructure, is rated 5 or 6 on the FHWA's 0 to 9 scale. A 6 means minor deterioration, while a 5 means the element is structurally sound but shows section loss, cracking, or spalling.

The lowest-component rule means the label compresses very different structures into one word. A bridge can be rated 8 on deck and superstructure with a 5 on the substructure, and be classified as Fair. But so is a bridge rated 6 on all three. The first bridge has a localized problem on the component that carries the whole structure and is the hardest to inspect. The second bridge is simply aging uniformly.

So in general, the Fair category contains both bridges that will coast for another decade and bridges that will cross the line to Poor condition at their next inspection.

How many "Fair" bridges are there?

The ASCE 2025 Infrastructure Report Card counts more than 623,000 bridges in the USA, with 49.1% rated Fair, 44.1% Good, and 6.8% Poor. Fair has been the largest category for years. ARTBA's analysis of the 2025 NBI data estimates the Fair share at 50%. Over the past five years the share of Fair bridges has grown while both the Good and the Poor shares declined.

The share of Poor bridges is declining because federal money prioritizes these structures. These projects replace and rehabilitate Poor bridges, whose share fell from 7.4% in 2019 to 6.8% in 2023 and 6.7% in the latest data. The Bridge Formula Program created by the 2021 infrastructure law distributes $27.5 billion to states over five years, and the apportionment formula weights 75% toward the cost of replacing Poor bridges and 25% toward rehabilitating Fair ones. It is a reasonable allocation, but it means a category with seven times the bridges competes for a quarter of the funding.

The percentage of Good bridges is falling because the cohort of interstate-era bridges built in the 1950s through 1970s is aging past the 7 threshold.

The scale of the problem

The number of "Fair" bridges is not exactly a safety problem, as most of these structures are still well-equipped to remain in service for a lot of years. However, the growing number of these bridges is both an opportunity for cost-saving and a problem that will need to be addressed in the future.

ARTBA's analysis of the same NBI data finds that one bridge in three needs repair or replacement and estimates the cost of all identified repairs at over $319 billion. At the current pace, repairing only the Poor bridges alone would take nearly 75 years. Seeing how the bridges in Poor condition are only a small part of all the bridges, and the Fair bridges are not so far from becoming Poor condition, the problem will only get worse without more investment.

Having ever more bridges come closer to the point of repair means the state of bridges in the next decade depends on whether the Fair stock gets preserved now, at preservation cost, or replaced later, at replacement cost. On the same structure, preserving is a fraction of the replacement. When federal funds are concentrated almost solely on the Poor bridges, it means money is always spent on the most costly operations and almost no money is allocated to the more efficient operations of preservation.

What should change

ASCE's own report card notes that Fair bridges can be preserved at a lower cost than Poor bridges can be rehabilitated. A deck overlay or a joint replacement on a bridge rated 5 costs a fraction of the superstructure rehabilitation the same bridge needs after five more winters of chloride penetration. What is mostly the problem is to know which of the hundreds of Fair bridges is deteriorating fast enough to justify investment.

The first part of the solution is committing the money that already exists. As of July 2025, states had committed 55% of the Bridge Formula Program funds available to them, and states can also direct flexible federal highway funds, National Highway Performance Program and Surface Transportation Block Grant money among them, toward bridge preservation.

The second part is spending a larger amount on bridges above the Poor line. The 75/25 formula weighting is fixed in law, but nothing prevents a state from running its own preservation-first program on the Fair stock.

The third part of the solution is having more and better information. Preservation-first only works if the owner knows which of several hundred Fair bridges to treat this year, and the NBI refresh cycle cannot answer that. The 2022 NBIS update already allows risk-based inspection intervals. Pairing that flexibility with continuous data on the bridges that drive the risk ranking is the missing operational layer.

24-month inspections don't suffice

Under the National Bridge Inspection Standards, most bridges receive a routine inspection every 24 months. The 2022 update to the standards allows risk-based intervals, which can extend the cycle to 48 months for low-risk structures, and underwater inspections run on a 60-month cycle.

For a Fair bridge, this cadence means the rating can be nearly two years old on the day a funding decision is made. Inspections are absolutely crucial for maintenance, but even with regular visits, a bridge can move from a 5 rating to a 4 three months after an inspection.

Inspections are also visual methods, which have their limits. Although a lot of changes are readily visible because cracks and other symptoms follow a somewhat predictable logic, there are changes that are not easily noticed by eye. The first is slow structural change that has no visible expression, such as the loss of global stiffness that shows up as a drift of a few tenths of a percent in the bridge's natural frequencies. The second is transient events, overloads, impacts from vessels or vehicles, which all happen between visits and leave consequences that a later inspection must reconstruct from effects.

Managing a "Fair" bridge

In cases when a bridge is already at risk or not in good health, regular inspection should be supplemented with continuous monitoring. Sensors along a structure help understand any changes over years and help identify moments that could have caused damage to the structure. With modern monitoring software, an overload on a bridge can be caught with sensors, and a system can send a warning to the team responsible for upkeep.

One case where monitoring would be necessary is a 5 on the substructure of a bridge over water, because scour is the most commonly cited cause of US bridge failure. The second is non-redundant structural schemes, cable-stayed and truss spans among them, where a single element's condition is crucial for the structure and much of that element is hidden inside sheathing or connections. The third is consequence, the high-ADT crossing whose closure would cost more per month in detours than a monitoring system costs in total.

West Virginia's DOT applied this logic to the East Huntington Bridge, a cable-stayed span over the Ohio River carrying more than 14,000 vehicles a day, in a state where roughly one bridge in five needs targeted structural improvement. Funded by an FY2022 SMART grant and run with Marshall University and HNTB, the wireless network did what visual inspection of sheathed stays cannot. The data revealed vortex-induced vibrations on several stay cables, which explained a history of premature damper failures, and flagged insufficient tension in stays, which prompted intervention before the condition rating ever moved.

Frequently Asked Questions

Is a Fair bridge safe to drive on?

Yes. Fair means the weakest component shows deterioration, not that the bridge is deficient, and even Poor bridges remain open under inspection, often with load limits, until repair. The classification is a maintenance and funding flag, not a safety verdict. Safety decisions come from load ratings and inspections, not from the category label.

How close is a Fair bridge to being reclassified as Poor?

One or two grades, depending on its ratings. A bridge whose lowest component is rated 6 has a grade of margin. A bridge with a 5 crosses into Poor the first time an inspector downgrades that component, and the NBI does not distinguish the two cases in the published category.

Can continuous monitoring change a bridge's condition rating?

No. Ratings come from NBIS inspections, and sensors do not substitute for them. Monitoring changes what happens between ratings. It catches frequency drift, tilt trends, and transient events while they occur, so the owner can schedule intervention, or a targeted inspection, before the next routine visit finds the damage.

Which Fair bridges should be instrumented first?

Bridges rated 5 on the substructure over water, non-redundant schemes such as cable-stayed or truss spans, and high-traffic crossings whose closure cost dwarfs the monitoring cost.

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