Total bridges
613
Public highway bridges in Allen County
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.
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.
When Allen County's bridges were built
613 bridges with a recorded construction year, grouped by decade
- pre-1900 6
Built before 1900
6 bridges
- 1900s 7
1900–1909
7 bridges
- 1910s 5
1910–1919
5 bridges
- 1920s 5
1920–1929
5 bridges
- 1930s 22
1930–1939
22 bridges
- 1940s 15
1940–1949
15 bridges
- 1950s 31
1950–1959
31 bridges
- 1960s
1960–1969
89 bridges
- 1970s
1970–1979
127 bridges
- 1980s
1980–1989
99 bridges
- 1990s
1990–1999
98 bridges
- 2000s 41
2000–2009
41 bridges
- 2010s
2010–2019
51 bridges
- 2020s 17
2020–2029
17 bridges
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.
| 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.
Good-condition bridges (255)
AIRPORT EXPY
GoodOver: WELLBAUM DRAIN
00.06 E COVERDALE RD, Allen, IN
Built 1995 Load: 90.7 t ADT: 10,125
SR 101
GoodOver: SMITH-FRY DITCH
02.23 S SR 37, Allen, IN
Built 1991 Load: 97.2 t ADT: 1,157
I-469
GoodOver: SIX MILE CREEK
01.90 N US 24, Allen, IN
Built 1992 Load: 97.2 t ADT: 33,629
I-469
GoodOver: MARTIN DITCH
01.19 E I-69, Allen, IN
Built 1995 Load: 97.2 t ADT: 44,507
US 24
GoodOver: GROVER DITCH
03.88 W SR 101, Allen, IN
Built 2010 Load: 97.2 t ADT: 17,611
Read our methodology - how this data is sourced, computed, and verified.
Related
Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainBridges
Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.