County profile · official public datasets

Seneca County, OH

275 public highway bridges tracked in the FHWA National Bridge Inventory: 72.7% rated Good, 25.8% Fair, 1.5% Poor.

275
Public bridges: 72.7%
Good condition: 1.5%
Poor condition

The verdict

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

Seneca County pairs a top-quartile lowest Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

Top 17%
lowest Poor share in state: 1.5%
Poor-condition share: 275
public highway bridges: 1983
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.

Seneca County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Seneca County ranks #15 of 88 Ohio counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 1.5%). Seneca County, Ohio contains 275 public highway bridges. Roughly 72.7% are rated “Good,” 25.8% “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

275

Public highway bridges in Seneca County

Good condition

72.7%

200 of 275 rated 7-9

Fair condition

25.8%

71 of 275 rated 5-6

Poor condition

1.5%

4 of 275 rated 4 or below

In-state Poor-share rank

#15 of 88

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

Condition distribution

Share of 275 NBI-tracked bridges by lowest applicable component rating.

Good

72.7% (200)

Fair

25.8% (71)

Poor

1.5% (4)

Seneca County's Poor-condition bridges carry 2,687 vehicle crossings a day

That is 1% of the county's reported daily bridge traffic on 1.1% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 896 crossings a day against 988 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 274 of 275 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

33.1% of Seneca County's bridges have passed the 50-year mark

91 of the 275 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 72.7% 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 63.3% of the county's Poor-condition bridge traffic

RIVER RD. over WILLOW CREEK, built 1914, carries 1,701 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 4-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 2,687 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

3
1910s

4
1920s

2
1930s

4
1940s

7
1950s

21
1960s

36
1970s

28
1980s

58
1990s

42
2000s

38
2010s

24
2020s

8

What this shows Construction peaked in the 1980s, when 58 of the county's bridges still in the inventory were built, which is 21.1% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year is 1983, 6 years newer than the Ohio average of 1977.

How Seneca County compares with Ohio's closest counties by inventory size

The 5 Ohio counties nearest Seneca County in number of bridges, with their condition splits. Its 1.5% Poor share is the 2nd-lowest of these 6. Its average build year of 1983 against a peer-group mean of 1982 is in line with the group.

Showing the 5 closest of 87 Ohio counties eligible for comparison.

Bridge inventory size and condition shares for Seneca County and the 5 Ohio counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Logan County	281	78.3%	20.6%	1.1%	1979
Shelby County	277	74%	23.5%	2.5%	1989
Hardin County	276	64.1%	28.6%	7.2%	1979
Seneca County (this page)	275	72.7%	25.8%	1.5%	1983
Knox County	274	54.4%	40.1%	5.5%	1980
Delaware County	268	70.5%	27.2%	2.2%	1982

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

Similar inventory size

Nearest county inventories outside OH (275 bridges here).

Walker County, AL · 275 bridges
Ellis County, KS · 275 bridges
Harford County, MD · 275 bridges
Lyon County, IA · 276 bridges

Similar average build year

Nearest mean year-built outside OH (1983 here).

Dallas County, TX · avg 1983 · 3,230 bridges
Bexar County, TX · avg 1983 · 2,342 bridges
Sedgwick County, KS · avg 1983 · 1,333 bridges
Will County, IL · avg 1983 · 649 bridges

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

All 275 Good 200 Fair 71 Poor 4

Good-condition bridges (200)

Sort:

Seneca County Bridge Snapshot

Condition distribution

Seneca County's Poor-condition bridges carry 2,687 vehicle crossings a day

33.1% of Seneca County's bridges have passed the 50-year mark

One structure carries 63.3% of the county's Poor-condition bridge traffic

How Seneca County compares with Ohio's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

Good-condition bridges (200)

SR 19

SR 19

SR 19

SR 101

SR 228

SR 587

HOP TR-18

ADA TR 179

CR 49

BLO TR 77

JAC TR 36

LIB TR 154

SCI CR 38

SEN TR 98

TR 79

THO TR 81

TR 136

CLI CR 13

LOU CR 38

CLI TR 73

HOP TR 110

HOP CR 52

SR 4

SR 18

USR 224

BLO TR 181

BLO CR 43

CLI TR130

EDE CR 16

EDE TR 42

PLE CR 34

BSP TR 101

EDE CR 6

LOU TR 116

VEN TR 187

HOP CR 38

REE TR 124

JAC TR 45

JAC TR 84

THO CR 27

SR 12

SR 19

SR 67

SR 101

SR 587

ADA TR 179

BSP CR 45

CLI TR 165

JAC CR 592

LIB CR 592

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