County profile · official public datasets

Allen County, IN

613 public highway bridges tracked in the FHWA National Bridge Inventory: 41.6% rated Good, 51.5% Fair, 6.9% Poor.

613
Public bridges: 41.6%
Good condition: 6.9%
Poor condition

The verdict

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

Allen County posts a higher-than-median Poor-condition share among rated counties in the state across large county bridge inventory.

69th
of 92 on Poor share: 6.9%
Poor-condition share: 613
public highway bridges: 1978
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.

Allen County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Allen County ranks #69 of 92 Indiana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.9%). Allen County, Indiana contains 613 public highway bridges. Roughly 41.6% are rated “Good,” 51.5% “Fair,” and 6.9% “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

613

Public highway bridges in Allen County

Good condition

41.6%

255 of 613 rated 7-9

Fair condition

51.5%

316 of 613 rated 5-6

Poor condition

6.9%

42 of 613 rated 4 or below

In-state Poor-share rank

#69 of 92

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

Condition distribution

Share of 613 NBI-tracked bridges by lowest applicable component rating.

Good

41.6% (255)

Fair

51.5% (316)

Poor

6.9% (42)

Allen County's Poor-condition bridges carry 148,286 vehicle crossings a day

That is 3.4% of the county's reported daily bridge traffic on 6.9% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 3,531 crossings a day against 10,282 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 613 of 613 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

40.6% of Allen County's bridges have passed the 50-year mark

249 of the 613 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 41.6% 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 15.7% of the county's Poor-condition bridge traffic

BLUFFTON RD over ST MARYS RIVER, built 1986, carries 23,300 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 42-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 148,286 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

pre-1900

6
1900s

7
1910s

5
1920s

5
1930s

22
1940s

15
1950s

31
1960s

89
1970s

127
1980s

99
1990s

98
2000s

41
2010s

51
2020s

17

What this shows Construction peaked in the 1970s, when 127 of the county's bridges still in the inventory were built, which is 20.7% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1978) matches the Indiana average (1978).

How Allen County compares with Indiana's closest counties by inventory size

The 5 Indiana counties nearest Allen County in number of bridges, with their condition splits. Its 6.9% Poor share is the 6th-lowest of these 6. Its average build year of 1978 against a peer-group mean of 1983 is 5 years older.

Showing the 5 closest of 91 Indiana counties eligible for comparison.

Bridge inventory size and condition shares for Allen County and the 5 Indiana counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Allen County (this page)	613	41.6%	51.5%	6.9%	1978
Lake County	501	51.1%	42.9%	6%	1984
Hamilton County	454	68.3%	29.1%	2.6%	1996
Gibson County	362	42.8%	53%	4.1%	1978
Hendricks County	355	41.4%	56.3%	2.3%	1982
Wayne County	343	41.1%	54.8%	4.1%	1975

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

Similar inventory size

Nearest county inventories outside IN (613 bridges here).

Weld County, CO · 614 bridges
Mobile County, AL · 612 bridges
Monroe County, NY · 615 bridges
Palm Beach County, FL · 610 bridges

Similar average build year

Nearest mean year-built outside IN (1978 here).

Orange County, CA · avg 1978 · 1,164 bridges
Sumner County, KS · avg 1978 · 659 bridges
Livingston County, IL · avg 1978 · 579 bridges
Buncombe County, NC · avg 1978 · 555 bridges

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

All 613 Good 255 Fair 316 Poor 42

Good-condition bridges (255)

Sort:

Allen County Bridge Snapshot

Condition distribution

Allen County's Poor-condition bridges carry 148,286 vehicle crossings a day

40.6% of Allen County's bridges have passed the 50-year mark

One structure carries 15.7% of the county's Poor-condition bridge traffic

How Allen County compares with Indiana'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 (255)

SR 3 NB

SR 3 SB

BULL RAPIDS ROAD

US 24 EB

I-469 WB

US 30/33 SR 930

US 24 WB

SR 37

SWIFTS RUN

TONKEL RD

MARION CENTER ROAD

I-469 NB

BASS RD

FACKLER RD

I-469 SB

YODER ROAD

I-469 NB

WINCHESTER RD

OLD MAYSVILLE RD

PRINE RD

S COUNTY LINE RD

SR 37

ABOITE CENTER ROAD

COLDWATER ROAD NB

STELLHORN ROAD

US 24 EB

US 24 WB

BERTHAUD RD

STATE LINE ROAD

YOHNE ROAD

OLD LIMA RD

I-69 SB

MARION CENTER RD

SR 930 EB

I-69 NB

KILLIAN RD

I-469 WB

COVERDALE RD

OLD 24

LIMA RD

W JEFFERSON BLVD

I-69 NB

I-69 SB

STATE BOULEVARD

ODAY ROAD

SR 1

US 30 EB

I-69 NB ON-RAMP

WILLOW RIDGE TRAIL

WEST HAMILTON RD

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