County profile · official public datasets

Piatt County, IL

246 public highway bridges tracked in the FHWA National Bridge Inventory: 62.2% rated Good, 31.7% Fair, 6.1% Poor.

246
Public bridges: 62.2%
Good condition: 6.1%
Poor condition

The verdict

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

Piatt County posts a better-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.

Top 26%
lowest Poor share in state: 6.1%
Poor-condition share: 246
public highway bridges: 1979
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.

Piatt County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Piatt County ranks #27 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.1%). Piatt County, Illinois contains 246 public highway bridges. Roughly 62.2% are rated “Good,” 31.7% “Fair,” and 6.1% “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

246

Public highway bridges in Piatt County

Good condition

62.2%

153 of 246 rated 7-9

Fair condition

31.7%

78 of 246 rated 5-6

Poor condition

6.1%

15 of 246 rated 4 or below

In-state Poor-share rank

#27 of 102

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

Condition distribution

Share of 246 NBI-tracked bridges by lowest applicable component rating.

Good

62.2% (153)

Fair

31.7% (78)

Poor

6.1% (15)

Piatt County's Poor-condition bridges carry 16,750 vehicle crossings a day

That is 6.3% of the county's reported daily bridge traffic on 6.1% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 1,117 crossings a day against 521 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 246 of 246 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

33.7% of Piatt County's bridges have passed the 50-year mark

83 of the 246 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 62.2% 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 32.5% of the county's Poor-condition bridge traffic

I-72 (EB) over Norfolk Southern Railway, built 1975, carries 5,450 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 15-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 16,750 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

3
1930s

10
1940s

1
1950s

10
1960s

39
1970s

60
1980s

52
1990s

36
2000s

21
2010s

12
2020s

2

What this shows Construction peaked in the 1970s, when 60 of the county's bridges still in the inventory were built, which is 24.4% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1979) matches the Illinois average (1979).

How Piatt County compares with Illinois's closest counties by inventory size

The 5 Illinois counties nearest Piatt County in number of bridges, with their condition splits. Its 6.1% Poor share is the 3rd-lowest of these 6. Its average build year of 1979 against a peer-group mean of 1974 is 5 years newer.

Showing the 5 closest of 101 Illinois counties eligible for comparison.

Bridge inventory size and condition shares for Piatt County and the 5 Illinois counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Effingham County	253	47.4%	47.8%	4.7%	1974
Lake County	251	37.1%	53%	10%	1976
Piatt County (this page)	246	62.2%	31.7%	6.1%	1979
Macoupin County	242	36.4%	45.9%	17.8%	1965
Morgan County	234	48.7%	42.7%	8.5%	1984
Washington County	233	50.6%	43.3%	6%	1973

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 Piatt 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 Piatt County, both outside Illinois so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside IL (246 bridges here).

Cullman County, AL · 246 bridges
Jackson County, IA · 246 bridges
Jackson County, KS · 246 bridges
Buchanan County, MO · 246 bridges

Similar average build year

Nearest mean year-built outside IL (1979 here).

Pima County, AZ · avg 1979 · 1,150 bridges
Jefferson County, KY · avg 1979 · 662 bridges
Spartanburg County, SC · avg 1979 · 638 bridges
McPherson County, KS · avg 1979 · 586 bridges

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

All 246 Good 153 Fair 78 Poor 15

All bridges (246)

Sort:

Piatt County Bridge Snapshot

Condition distribution

Piatt County's Poor-condition bridges carry 16,750 vehicle crossings a day

33.7% of Piatt County's bridges have passed the 50-year mark

One structure carries 32.5% of the county's Poor-condition bridge traffic

How Piatt County compares with Illinois'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 (246)

TR-73

ILLINOIS ST(MS 710

TR 85

I-74 (EB)

IL 48(FAP 760)

TR 80

TR 121

FAP 756 (BRIDGE ST

TR 80

CH 9

FAS 541(CH 6)

FAS 538(CH 5)

CH 14

TR 51

FAS 1517(US 150)

Bridge Street

TR 96

TR 195

TR 105

IL 105(FAP 741)

IL 10 (FAP 721)

TR 170

TR 183

FAS 1517(US 150)

IL 10 (FAP 721)

TR 105

ILL 10(FAP 721)

US 150 (FAS 1517)

TR 105

I-74

FAS 495

FAU 7531

SBI 10 (FAS 1532)

TR 126

TR 135

TR 156(FAS 1530)

TR 56

TR 59

TR 171

TR 207

FAS 1532 (TR 154)

TR 4

ILL 10(FAP 721)

TR 27

I-72 (EB)

I-72 (WB)

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