County profile · official public datasets

Knox County, TN

588 public highway bridges tracked in the FHWA National Bridge Inventory: 49.8% rated Good, 48.6% Fair, 1.5% Poor.

Compiled by PlainBridges

588
Public bridges: 49.8%
Good condition: 1.5%
Poor condition

The verdict

According to the Federal Highway Administration's 2024 National Bridge Inventory.

Knox County posts a top-quartile lowest Poor-condition share among rated counties in the state across large county bridge inventory.

Top 14%
lowest Poor share in state: 1.5%
Poor-condition share: 588
public highway bridges: 1974
avg year built

Poor is an FHWA condition category from the lowest applicable component rating (4 or below), not a live crossing-safety or closure decision. Rankings cover counties with at least five public highway bridges.

Knox County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Knox County ranks #13 of 95 Tennessee counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 1.5%). Knox County, Tennessee contains 588 public highway bridges. Roughly 49.8% are rated “Good,” 48.6% “Fair,” and 1.5% “Poor.” Poor means the lowest applicable deck, superstructure, substructure, or culvert rating is 4 or below on the 0–9 NBI scale. It is a condition category, not a live safety or closure decision.

Responsible agencies inspect covered bridges on risk-based intervals under current NBIS rules and submit inventory data to FHWA annually. The list below shows every NBI-tracked bridge in the county. Use the “Sort by” controls to change the ordering, and click any row for its reported inspection date, traffic count, and condition fields.

Source: FHWA National Bridge Inventory. See methodology for full definitions.

Total bridges

588

Public highway bridges in Knox County

Good condition

49.8%

293 of 588 rated 7-9

Fair condition

48.6%

286 of 588 rated 5-6

Poor condition

1.5%

9 of 588 rated 4 or below

In-state Poor-share rank

#13 of 95

Among Tennessee counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 588 NBI-tracked bridges by lowest applicable component rating.

Good

49.8% (293)

Fair

48.6% (286)

Poor

1.5% (9)

Knox County's Poor-condition bridges carry 448,854 vehicle crossings a day

That is 2.5% of the county's reported daily bridge traffic on 1.5% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 49,873 crossings a day against 34,910 for a Good-condition one. A Poor rating is a condition category, not a closure or a live safety judgement; it means the lowest applicable component rating is 4 or below.

Computed over the 588 of 588 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

52.6% of Knox County's bridges have passed the 50-year mark

309 of the 588 bridges with a recorded construction year were built in 1974 or earlier. Age alone is not a defect: a well-maintained older bridge can rate Good, and 49.8% of this county's inventory does. Even so, this older cohort is the population from which future Poor ratings are drawn, which is why the age profile below matters alongside the condition split above.

Cutoff derives from the 2024 release year minus a 50-year design life. Source: FHWA National Bridge Inventory, 2024 release.

One structure carries 31.1% of the county's Poor-condition bridge traffic

I40 over I40 / UNIVERSITY AVE., built 1965, carries 139,697 vehicles a day, the most of any Poor-rated structure here. The county's Poor-condition exposure is concentrated rather than evenly spread, so the 9-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 448,854 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

pre-1900

2
1900s

1
1910s

5
1920s

10
1930s

48
1940s

36
1950s

40
1960s

116
1970s

63
1980s

86
1990s

76
2000s

68
2010s

26
2020s

11

What this shows Construction peaked in the 1960s, when 116 of the county's bridges still in the inventory were built, which is 19.7% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1974) matches the Tennessee average (1977).

How Knox County compares with Tennessee's closest counties by inventory size

The 5 Tennessee counties nearest Knox County in number of bridges, with their condition splits. Its 1.5% Poor share is the 1st-lowest of these 6. Its average build year of 1974 against a peer-group mean of 1979 is 5 years older.

Showing the 5 closest of 94 Tennessee counties eligible for comparison.

Bridge inventory size and condition shares for Knox County and the 5 Tennessee counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Knox County (this page)	588	49.8%	48.6%	1.5%	1974
Williamson County	520	63.5%	33.1%	3.5%	1984
Hamilton County	464	46.8%	47%	6.3%	1976
Rutherford County	428	60.3%	35.5%	4.2%	1977
Maury County	424	22.9%	70.8%	6.4%	1975
Madison County	418	31.8%	64.1%	4.1%	1983

Each share is of that county's own total tracked bridges; peers are the counties with 5 or more bridges whose inventory size is closest to Knox County's. Source: FHWA National Bridge Inventory, 2024 release.

Nationwide counties with similar inventory size or average build year

Two NBI-derived peer sets for Knox County, both outside Tennessee so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside TN (588 bridges here).

Tulare County, CA · 589 bridges
Dane County, WI · 590 bridges
McPherson County, KS · 586 bridges
Butler County, KS · 591 bridges

Similar average build year

Nearest mean year-built outside TN (1974 here).

Summit County, OH · avg 1974 · 563 bridges
Onondaga County, NY · avg 1974 · 472 bridges
Orange County, NY · avg 1974 · 472 bridges
Pierce County, WA · avg 1974 · 472 bridges

Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.

All 588 Good 293 Fair 286 Poor 9

All bridges (588)

Sort:

Knox County Bridge Snapshot

Condition distribution

Knox County's Poor-condition bridges carry 448,854 vehicle crossings a day

52.6% of Knox County's bridges have passed the 50-year mark

One structure carries 31.1% of the county's Poor-condition bridge traffic

How Knox County compares with Tennessee's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

All bridges (588)

FAU 5649

I40

I40

I40

I40

I40

NFA 5666

FAP 115 RAMP

I40

I40

I40

I40

I40

I40 RMP

I40 RMP

FAU 1053

I40

I40 RAMP 5-C

I40 RAMP 5-H

I140

FAP 162

I40

FAP 158

I40

I40 RMP

I40

I40

I40

I40

WB FRONTAGE RD.

FAU 5289

FAP 158

SR-1

SR 33

I40 RMP C-C

I75 RP D-D

I75 RL

NFA A823

I75 RL&LL

NFA B150

I75 RL 730818L

I75 RL

I75 LL

I75 RL & RMP

I75 LL

I140

I140

I140

I140

I140

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