Total bridges
80
Public highway bridges in Carbon County
County profile · official public datasets
Carbon County, MT
80 public highway bridges tracked in the FHWA National Bridge Inventory: 36.3% rated Good, 58.8% Fair, 5% Poor.
- 80
- Public bridges
- 36.3%
- Good condition
- 5%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Carbon County pairs a better-than-median Poor-condition share among rated counties in the state with a newer average build year than the state inventory.
- Top 36%
- lowest Poor share in state
- 5%
- Poor-condition share
- 80
- public highway bridges
- 1985
- 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.
Carbon County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Carbon County ranks #20 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 5%). Carbon County, Montana contains 80 public highway bridges. Roughly 36.3% are rated “Good,” 58.8% “Fair,” and 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.
Good condition
36.3%
29 of 80 rated 7-9
Fair condition
58.8%
47 of 80 rated 5-6
Poor condition
5%
4 of 80 rated 4 or below
In-state Poor-share rank
#20 of 56
Among Montana counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 80 NBI-tracked bridges by lowest applicable component rating.
Good 36.3% (29)
Fair 58.8% (47)
Poor 5% (4)
Carbon County's Poor-condition bridges carry 678 vehicle crossings a day
That is 1.5% of the county's reported daily bridge traffic on 5% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 170 crossings a day against 597 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 80 of 80 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
35% of Carbon County's bridges have passed the 50-year mark
28 of the 80 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 36.3% 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 70.5% of the county's Poor-condition bridge traffic
S 78 FH 83 over RED LODGE CREEK, built 1953, carries 478 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 678 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Carbon County's bridges were built
80 bridges with a recorded construction year, grouped by decade
- 1910s 3
1910–1919
3 bridges
- 1930s 3
1930–1939
3 bridges
- 1940s 2
1940–1949
2 bridges
- 1950s
1950–1959
8 bridges
- 1960s 3
1960–1969
3 bridges
- 1970s
1970–1979
12 bridges
- 1980s
1980–1989
11 bridges
- 1990s 4
1990–1999
4 bridges
- 2000s
2000–2009
12 bridges
- 2010s
2010–2019
17 bridges
- 2020s 5
2020–2029
5 bridges
What this shows Construction peaked in the 2010s, when 17 of the county's bridges still in the inventory were built, which is 21.3% of those with a recorded year. That cohort is now 5 to 14 years old in the 2024 inventory. Its average build year is 1985, 8 years newer than the Montana average of 1977.
How Carbon County compares with Montana's closest counties by inventory size
The 5 Montana counties nearest Carbon County in number of bridges, with their condition splits. Its 5% Poor share is the 4th-lowest of these 6. Its average build year of 1985 against a peer-group mean of 1975 is 10 years newer.
Showing the 5 closest of 55 Montana counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Stillwater County | 92 | 30.4% | 68.5% | 1.1% | 1977 |
| Teton County | 82 | 42.7% | 54.9% | 2.4% | 1975 |
| Carbon County (this page) | 80 | 36.3% | 58.8% | 5% | 1985 |
| Granite County | 73 | 37% | 52.1% | 11% | 1974 |
| Custer County | 71 | 14.1% | 84.5% | 1.4% | 1969 |
| Glacier County | 71 | 38% | 56.3% | 5.6% | 1978 |
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 Carbon 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 Carbon County, both outside Montana so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside MT (80 bridges here).
- Moffat County, CO · 80 bridges
- Burke County, GA · 80 bridges
- Gooding County, ID · 80 bridges
- Madison County, ID · 80 bridges
Similar average build year
Nearest mean year-built outside MT (1985 here).
- Hillsborough County, FL · avg 1985 · 840 bridges
- Lancaster County, NE · avg 1985 · 661 bridges
- Nueces County, TX · avg 1985 · 528 bridges
- Grayson County, TX · avg 1985 · 513 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
All bridges (80)
CHERRY SPRINGS RD
FairOver: CLEAR CREEK 062
1M E ROBERTS, Carbon, MT
Built 1942 ADT: 100
RED LODGE CR RD
FairOver: VOLNEY CREEK 015
13M SW BOYD, Carbon, MT
Built 1991 Load: 4.5 t ADT: 100
BLUEWATER RD
FairOver: BLUEWATER CREEK 038
3M SE FROMBERG, Carbon, MT
Built 1915 Load: 6.4 t ADT: 100
BOYD COONEY DAM RD
FairOver: RED LODGE CREEK 013
COONEY RESERVOIR DAM, Carbon, MT
Built 1991 Load: 14.5 t ADT: 564
2-LANE ROAD
FairOver: WEST FORK ROCK CREEK
8 MILES WEST OF RED LODGE, Carbon, MT
Built 1965 Load: 15.2 t ADT: 50
1-LANE ROAD
FairOver: WEST ROSEBUD CREEK
9 MILES SW OF ROSCOE, Carbon, MT
Built 1959 Load: 16.2 t ADT: 50
1-LANE ROAD
FairOver: WEST FORK ROCK CREEK
11 MILES W. OF RED LODGE, Carbon, MT
Built 1956 Load: 17.5 t ADT: 50
E ROSEBUD RD
FairOver: EAST ROSEBUD CREEK 017
ROSCOE, Carbon, MT
Built 2010 Load: 18.5 t ADT: 76
LONE TREE RD
FairOver: RED LODGE CREEK 045
1M NW BOYD, Carbon, MT
Built 1972 Load: 19.8 t ADT: 100
BOYD COONEY DAM RD
FairOver: ROCK CREEK 027
1M W BOYD, Carbon, MT
Built 1973 Load: 21.7 t ADT: 564
E ROSEBUD RD
FairOver: EAST ROSEBUD CREEK 018
2M SW ROSCOE, Carbon, MT
Built 1993 Load: 21.7 t ADT: 76
1-LANE ROAD
FairOver: MAIN FORK ROCK CREEK
NO DATA ENTERED, Carbon, MT
Built 1952 Load: 22.0 t ADT: 50
S 78 FH 83
FairOver: EAST ROSEBUD CREEK
ROSCOE, Carbon, MT
Built 1959 Load: 22.7 t ADT: 478
NO DATA ENTERED
FairOver: LAKE FORK ROCK CREEK
NO DATA ENTERED, Carbon, MT
Built 1952 Load: 23.3 t ADT: 50
BRIDGER FROMBERG R
FairOver: BLUEWATER CREEK 001
2M SE FROMBERG, Carbon, MT
Built 1913 Load: 24.5 t ADT: 218
LOWER RIVER RD
FairOver: BLUEWATER CREEK 002
1M SE FROMBERG, Carbon, MT
Built 1932 Load: 24.5 t ADT: 100
US 310
FairOver: ROCK CREEK
ROCKVALE, Carbon, MT
Built 1934 Load: 24.5 t ADT: 5,030
S 72
FairOver: CLARKS FORK YELLOWSTONE
4M NE BELFRY, Carbon, MT
Built 2011 Load: 25.4 t ADT: 1,722
1-LANE ROAD
FairOver: LAKE FORK ROCK CREEK
NO DATA ENTERED, Carbon, MT
Built 1952 Load: 25.9 t ADT: 50
S MAIN ST
FairOver: ROCK CREEK 046
JOLIET, Carbon, MT
Built 1987 Load: 26.3 t ADT: 891
RIVERVIEW LN
FairOver: CLARKS FK YELLOWSTNE 007
2M S BELFRY, Carbon, MT
Built 1981 Load: 26.3 t ADT: 100
FOX EAST BENCH RD
FairOver: ROCK CREEK 025
FOX, Carbon, MT
Built 2006 Load: 26.9 t ADT: 100
GIBSON RD
FairOver: ROCK CREEK 029
1M E ROCKVALE, Carbon, MT
Built 1979 Load: 26.9 t ADT: 31
19TH STREET
FairOver: ROCK CREEK 059
RED LODGE-19TH ST, Carbon, MT
Built 2012 Load: 26.9 t ADT: 359
VOLNEY CREEK RD
FairOver: RED LODGE CREEK 042
6M SE ROSCOE, Carbon, MT
Built 1930 Load: 27.2 t ADT: 100
US 310
FairOver: CLARKS FK YELLOWSTONE
2M S BRIDGER, Carbon, MT
Built 1971 Load: 28.1 t ADT: 2,245
DUTCH LN
FairOver: SILVERTIP CREEK 060
1M NE BELFRY, Carbon, MT
Built 2006 Load: 30.8 t ADT: 100
US 310
FairOver: BRIDGER CREEK
2M S BRIDGER, Carbon, MT
Built 1971 Load: 31.8 t ADT: 2,245
S 72
FairOver: CLARKS FORK YELLOWSTONE
5M S BELFRY, Carbon, MT
Built 1970 Load: 31.8 t ADT: 1,498
BOYD COONEY DAM RD
FairOver: COONEY RES SPILLWAY 014
7M W BOYD, Carbon, MT
Built 1982 Load: 32.7 t ADT: 564
RED LODGE CR RD
FairOver: E RED LODGE CREEK 010
8M W ROBERTS, Carbon, MT
Built 1970 Load: 32.7 t ADT: 100
TWO MILE BRIDGE RD
FairOver: ROCK CREEK 024
2M N RED LODGE, Carbon, MT
Built 1982 Load: 32.7 t ADT: 100
JOLIET FROMBERG RD
FairOver: ELBOW CREEK 035
2M SE JOLIET, Carbon, MT
Built 1979 Load: 32.7 t ADT: 173
CARBON AVE
FairOver: ROCK CREEK 026
1M E ROBERTS, Carbon, MT
Built 1982 Load: 32.7 t ADT: 100
E PRYOR RD
FairOver: CLARKS FK YELLOWSTNE 056
E EDGAR, Carbon, MT
Built 1980 Load: 32.7 t ADT: 411
E BRIDGER RD
FairOver: CLARKS FK YELLOWSTNE 055
E BRIDGER, Carbon, MT
Built 1980 Load: 32.7 t ADT: 258
GOLDEN LN
FairOver: CLARKS FK YELLOWSTNE 008
6M SW BRIDGER, Carbon, MT
Built 1981 Load: 32.7 t ADT: 100
US 212
FairOver: ROCK CREEK
1M W JOLIET, Carbon, MT
Built 1974 Load: 32.7 t ADT: 3,282
S 72
FairOver: CLARKS FORK YELLOWSTONE
1M N BELFRY, Carbon, MT
Built 2013 Load: 33.6 t ADT: 1,722
WILLOW CREEK RD
FairOver: WILLOW CREEK 061
7M SW ROBERTS, Carbon, MT
Built 1942 Load: 34.3 t ADT: 100
NO DATA ENTERED
FairOver: WEST FORK ROCK CREEK
NO DATA ENTERED, Carbon, MT
Built 1972 Load: 36.3 t ADT: 50
CHANCE RD
FairOver: CLARKS FK YELLOWSTNE 004
8M S BELFRY, Carbon, MT
Built 2004 Load: 36.3 t ADT: 100
US 310
FairOver: RR
16M SE BRIDGER, Carbon, MT
Built 2001 Load: 37.2 t ADT: 1,513
ACCESS ROAD
FairOver: LAYOUT CREEK
FROM N.P. VISITOR CENTER, Carbon, MT
Built 1983 Load: 38.1 t ADT: 23
1-LANE ROAD
FairOver: SOUTH FORK SPRING CREEK
8 MILES SW OF RED LODGE, Carbon, MT
Built 1979 Load: 39.9 t ADT: 50
RED LODGE CR RD
FairOver: RED LODGE CREEK 012
11M SW BOYD, Carbon, MT
Built 2005 Load: 49.5 t ADT: 100
LESLIE RD
FairOver: ELBOW CREEK 036
2M SW EDGAR, Carbon, MT
Built 1913 Load: 54.4 t ADT: 100
East Side Road
GoodOver: Rock Creek
4M S RED LODGE, Carbon, MT
Built 2023 ADT: 100
East Side Road
GoodOver: Rock Creek
7M S Red Lodge, Carbon, MT
Built 2023 ADT: 100
Meeteetse Trail
GoodOver: Rock Creek
1M SE of Red Lodge, Carbon, MT
Built 2023 ADT: 100
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.