County profile · official public datasets

Wibaux County, MT

25 public highway bridges tracked in the FHWA National Bridge Inventory: 12% rated Good, 84% Fair, 4% Poor.

25
Public bridges
12%
Good condition
4%
Poor condition

The verdict

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

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

Top 27%
lowest Poor share in state
4%
Poor-condition share
25
public highway bridges
1975
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.

Wibaux County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Wibaux County ranks #15 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 4%). Wibaux County, Montana contains 25 public highway bridges. Roughly 12% are rated “Good,” 84% “Fair,” and 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

25

Public highway bridges in Wibaux County

Good condition

12%

3 of 25 rated 7-9

Fair condition

84%

21 of 25 rated 5-6

Poor condition

4%

1 of 25 rated 4 or below

In-state Poor-share rank

#15 of 56

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

Condition distribution

Share of 25 NBI-tracked bridges by lowest applicable component rating.

Good
12% (3)
Fair
84% (21)
Poor
4% (1)

Wibaux County's Poor-condition bridges carry 38 vehicle crossings a day

That is 0.2% of the county's reported daily bridge traffic on 4% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 38 crossings a day against 618 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 25 of 25 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

64% of Wibaux County's bridges have passed the 50-year mark

16 of the 25 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 12% 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 100% of the county's Poor-condition bridge traffic

CARLYLE RD E over BEAVER CREEK, built 1960, carries 38 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 1-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 38 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Wibaux County's bridges were built

25 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1940s, when 5 of the county's bridges still in the inventory were built, which is 20% of those with a recorded year. That cohort is now 75 to 84 years old in the 2024 inventory. Its average build year (1975) matches the Montana average (1977).

Source FHWA National Bridge Inventory (year built) As of 2024 NBI release

How Wibaux County compares with Montana's closest counties by inventory size

The 5 Montana counties nearest Wibaux County in number of bridges, with their condition splits. Its 4% Poor share is the 3rd-lowest of these 6. Its average build year of 1975 against a peer-group mean of 1975 is in line with the group.

Showing the 5 closest of 55 Montana counties eligible for comparison.

Bridge inventory size and condition shares for Wibaux County and the 5 Montana counties closest to it in inventory size
County Bridges Poor
Garfield County 26 3.8%
Petroleum County 26 15.4%
Treasure County 26 15.4%
Wheatland County 26 7.7%
Wibaux County (this page) 25 4%
Powder River County 23 0%

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

Similar inventory size

Nearest county inventories outside MT (25 bridges here).

Similar average build year

Nearest mean year-built outside MT (1975 here).

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

All 25 Good 3 Fair 21 Poor 1

Fair-condition bridges (21)

PINE UNIT RD

Fair

Over: CEDAR CREEK 010

31M SW WIBAUX, Wibaux, MT

Built 1987 Load: 12.7 t ADT: 100

S 97

Fair

Over: INT W WIBAUX-I 94

NW OF WIBAUX, Wibaux, MT

Built 1962 Load: 21.8 t ADT: 261

S 7

Fair

Over: DRAINAGE-STOCKPASS

18M S WIBAUX, Wibaux, MT

Built 1942 Load: 25.4 t ADT: 624

S 7

Fair

Over: BEAVER CREEK

SOUTH EDGE OF WIBAUX, Wibaux, MT

Built 1949 Load: 25.4 t ADT: 1,661

S 7-LOG CABIN RD

Fair

Over: INT E WIBAUX I 94

NORTHEAST WIBAUX, Wibaux, MT

Built 1962 Load: 26.3 t ADT: 100

FRONTAGE ROAD 044

Fair

Over: INT ROCHLITZ I 94 001

5M W WIBAUX, Wibaux, MT

Built 1974 Load: 27.2 t ADT: 100

I 94

Fair

Over: INT CARLYLE RD

6M E WIBAUX, Wibaux, MT

Built 1974 Load: 28.1 t ADT: 1,792

I 94

Fair

Over: INT CARLYLE RD

6M E WIBAUX, Wibaux, MT

Built 1974 Load: 28.1 t ADT: 1,792

S 7

Fair

Over: ASH CREEK

25M S WIBAUX, Wibaux, MT

Built 1942 Load: 29.0 t ADT: 578

S 7

Fair

Over: DRAINAGE-STOCKPASS

17M S WIBAUX, Wibaux, MT

Built 1941 Load: 29.0 t ADT: 624

SAINT PHILIP RD

Fair

Over: DRAINAGE

15M SE WIBAUX, Wibaux, MT

Built 1954 Load: 29.0 t ADT: 40

COUNTY ROAD 031

Fair

Over: SMITH CREEK 007

29M N WIBAUX, Wibaux, MT

Built 2012 Load: 29.9 t ADT: 100

1ST AVE

Fair

Over: BEAVER CREEK 009

WIBAUX-1ST AVE, Wibaux, MT

Built 1986 Load: 29.9 t ADT: 100

EDGE HILL RD E

Fair

Over: BEAVER CREEK 017

18M S WIBAUX, Wibaux, MT

Built 1997 Load: 30.8 t ADT: 100

S 7

Fair

Over: RATTLESNAKE CREEK

22M S WIBAUX, Wibaux, MT

Built 1942 Load: 30.8 t ADT: 624

TRUCK ROUTE RD

Fair

Over: YATES CREEK 003

EAST WIBAUX, Wibaux, MT

Built 1939 Load: 35.4 t ADT: 53

BLACK DIAMOND RD

Fair

Over: BEAVER CREEK 011

6M SE WIBAUX, Wibaux, MT

Built 2017 Load: 37.2 t ADT: 46

I 94

Fair

Over: BEAVER CREEK

N WIBAUX, Wibaux, MT

Built 1962 Load: 46.3 t ADT: 1,609

I 94

Fair

Over: BEAVER CREEK

N WIBAUX, Wibaux, MT

Built 1974 Load: 49.9 t ADT: 1,792

I 94

Fair

Over: YATES CREEK

1M E WIBAUX, Wibaux, MT

Built 1962 Load: 99.9 t ADT: 3,583

I 94

Fair

Over: YATES CREEK

2M E WIBAUX, Wibaux, MT

Built 2000 Load: 99.9 t ADT: 3,583

Read our methodology - how this data is sourced, computed, and verified.

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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.