County profile · official public datasets

Winnebago County, WI

263 public highway bridges tracked in the FHWA National Bridge Inventory: 66.9% rated Good, 29.7% Fair, 3.4% Poor.

263
Public bridges: 66.9%
Good condition: 3.4%
Poor condition

The verdict

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

Winnebago 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 15%
lowest Poor share in state: 3.4%
Poor-condition share: 263
public highway bridges: 1992
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.

Winnebago County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Winnebago County ranks #11 of 72 Wisconsin counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 3.4%). Winnebago County, Wisconsin contains 263 public highway bridges. Roughly 66.9% are rated “Good,” 29.7% “Fair,” and 3.4% “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

263

Public highway bridges in Winnebago County

Good condition

66.9%

176 of 263 rated 7-9

Fair condition

29.7%

78 of 263 rated 5-6

Poor condition

3.4%

9 of 263 rated 4 or below

In-state Poor-share rank

#11 of 72

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

Condition distribution

Share of 263 NBI-tracked bridges by lowest applicable component rating.

Good

66.9% (176)

Fair

29.7% (78)

Poor

3.4% (9)

Winnebago County's Poor-condition bridges carry 7,513 vehicle crossings a day

That is 0.2% of the county's reported daily bridge traffic on 3.4% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 835 crossings a day against 11,493 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 263 of 263 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

15.2% of Winnebago County's bridges have passed the 50-year mark

40 of the 263 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 66.9% 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 83.9% of the county's Poor-condition bridge traffic

LRD NORTHERN ROAD over S BR MUD CREEK, built 1975, carries 6,300 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 9-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 7,513 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1920s

9
1930s

8
1950s

4
1960s

11
1970s

29
1980s

18
1990s

53
2000s

74
2010s

55
2020s

2

What this shows Construction peaked in the 2000s, when 74 of the county's bridges still in the inventory were built, which is 28.1% of those with a recorded year. That cohort is now 15 to 24 years old in the 2024 inventory. Its average build year is 1992, 8 years newer than the Wisconsin average of 1984.

How Winnebago County compares with Wisconsin's closest counties by inventory size

The 5 Wisconsin counties nearest Winnebago County in number of bridges, with their condition splits. Its 3.4% Poor share is the 1st-lowest of these 6. Its average build year of 1992 against a peer-group mean of 1985 is 7 years newer.

Showing the 5 closest of 71 Wisconsin counties eligible for comparison.

Bridge inventory size and condition shares for Winnebago County and the 5 Wisconsin counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Sauk County	271	53.9%	37.3%	8.9%	1984
Manitowoc County	269	44.6%	51.7%	3.7%	1983
Winnebago County (this page)	263	66.9%	29.7%	3.4%	1992
Trempealeau County	260	47.3%	41.2%	11.5%	1987
Fond du Lac County	251	53%	36.7%	10.4%	1986
La Crosse County	249	41%	53%	6%	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 Winnebago 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 Winnebago County, both outside Wisconsin so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside WI (263 bridges here).

Douglas County, CO · 263 bridges
Bingham County, ID · 263 bridges
Guthrie County, IA · 263 bridges
Henry County, MO · 263 bridges

Similar average build year

Nearest mean year-built outside WI (1992 here).

Johnson County, KS · avg 1992 · 781 bridges
Wake County, NC · avg 1992 · 760 bridges
Benton County, AR · avg 1992 · 410 bridges
Nodaway County, MO · avg 1992 · 396 bridges

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

All 263 Good 176 Fair 78 Poor 9

Good-condition bridges (176)

Sort:

Winnebago County Bridge Snapshot

Condition distribution

Winnebago County's Poor-condition bridges carry 7,513 vehicle crossings a day

15.2% of Winnebago County's bridges have passed the 50-year mark

One structure carries 83.9% of the county's Poor-condition bridge traffic

How Winnebago County compares with Wisconsin'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 (176)

CTH-Z

LRD AMERICAN DR

CTH-I

LRD MAIN STREET

LRD PENDLETON RD

LRD W FISK AVE

LRD SENN RD

LRD KNAPP ST RD

STH 26

LRD AMERICAN DR

LRD BUTTE DES MORT

STH 21-CONGRESS ST

STH 21-CONGRESS ST

CTH-BB

LRD OMRO RD

CTH-K

LRD CLAIRVILLE RD

CTH-CB

STH 116

STH 26

USH 10 WB

LRD BROOKS RD

USH 10 EB

CTH II

CTH K (W 20TH AVE)

LRD WISCONSIN STRE

LRD WISCONSIN STRE

LRD WISCONSIN STRE

LRD WISCONSIN STRE

STH 21

IH 41

USH 45

STH 116

STH 114-COMMERCIAL

USH 10 WB/STH 441

LRD BELL ST.

CTH GG

USH 441NB/USH 10 E

USH 10 EB/STH 441

STH 114 - TAYCO ST

USH 45

USH 45-STH 175

USH 45 SB OFF RAMP

USH 10 EB

STH 114-WINNECONNE

USH 10 EB

LRD LAKE BUTTE DES

USH 45 SB

USH 45 NB

LRD SKELETON BRIDG

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