Total bridges
47
Public highway bridges in Iosco County
County profile · official public datasets
Iosco County, MI
47 public highway bridges tracked in the FHWA National Bridge Inventory: 27.7% rated Good, 63.8% Fair, 8.5% Poor.
- 47
- Public bridges
- 27.7%
- Good condition
- 8.5%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Iosco County posts a better-than-median Poor-condition share among rated counties in the state across rated county bridge inventory.
- Top 42%
- lowest Poor share in state
- 8.5%
- Poor-condition share
- 47
- public highway bridges
- 1972
- 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.
Iosco County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Iosco County ranks #35 of 83 Michigan counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 8.5%). Iosco County, Michigan contains 47 public highway bridges. Roughly 27.7% are rated “Good,” 63.8% “Fair,” and 8.5% “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
27.7%
13 of 47 rated 7-9
Fair condition
63.8%
30 of 47 rated 5-6
Poor condition
8.5%
4 of 47 rated 4 or below
In-state Poor-share rank
#35 of 83
Among Michigan counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 47 NBI-tracked bridges by lowest applicable component rating.
Good 27.7% (13)
Fair 63.8% (30)
Poor 8.5% (4)
Iosco County's Poor-condition bridges carry 7,873 vehicle crossings a day
That is 7.2% of the county's reported daily bridge traffic on 8.5% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 1,968 crossings a day against 859 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 47 of 47 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
42.6% of Iosco County's bridges have passed the 50-year mark
20 of the 47 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 27.7% 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 55.3% of the county's Poor-condition bridge traffic
M-65 over JOHNSON CREEK, built 1950, carries 4,353 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 7,873 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Iosco County's bridges were built
47 bridges with a recorded construction year, grouped by decade
- 1910s 1
1910–1919
1 bridges
- 1920s 3
1920–1929
3 bridges
- 1930s 3
1930–1939
3 bridges
- 1950s
1950–1959
8 bridges
- 1960s 1
1960–1969
1 bridges
- 1970s
1970–1979
12 bridges
- 1980s
1980–1989
8 bridges
- 1990s 3
1990–1999
3 bridges
- 2000s
2000–2009
6 bridges
- 2010s 2
2010–2019
2 bridges
What this shows Construction peaked in the 1970s, when 12 of the county's bridges still in the inventory were built, which is 25.5% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1972) matches the Michigan average (1976).
How Iosco County compares with Michigan's closest counties by inventory size
The 5 Michigan counties nearest Iosco County in number of bridges, with their condition splits. Its 8.5% Poor share is the 2nd-lowest of these 6. Its average build year of 1972 against a peer-group mean of 1967 is 5 years newer.
Showing the 5 closest of 82 Michigan counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Crawford County | 54 | 14.8% | 66.7% | 18.5% | 1971 |
| Iron County | 54 | 20.4% | 59.3% | 20.4% | 1967 |
| Alger County | 53 | 30.2% | 58.5% | 11.3% | 1956 |
| Cass County | 52 | 25% | 59.6% | 15.4% | 1970 |
| Iosco County (this page) | 47 | 27.7% | 63.8% | 8.5% | 1972 |
| Roscommon County | 43 | 18.6% | 81.4% | 0% | 1970 |
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 Iosco 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 Iosco County, both outside Michigan so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside MI (47 bridges here).
- Juneau City and County, AK · 47 bridges
- Jackson County, CO · 47 bridges
- Ben Hill County, GA · 47 bridges
- Long County, GA · 47 bridges
Similar average build year
Nearest mean year-built outside MI (1972 here).
- Santa Clara County, CA · avg 1972 · 964 bridges
- Madison County, AL · avg 1972 · 710 bridges
- Kern County, CA · avg 1972 · 668 bridges
- York County, PA · avg 1972 · 569 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Fair-condition bridges (30)
BROOKS ROAD
FairOver: SILVER CREEK
600 FT S OF CURTIS ROAD, Iosco, MI
Built 1935 Load: 11.7 t ADT: 70
NATIONAL CITY RD
FairOver: AUGRES RIVER
0.50 MI S OF KEYSTONE, Iosco, MI
Built 1978 Load: 21.1 t ADT: 530
F 41
FairOver: VAN ETTAN CREEK
1MI NW OF US 23, Iosco, MI
Built 1979 Load: 26.2 t ADT: 12,300
US-23
FairOver: PRIVATE RR
2.2 MI N OF ARENAC COL, Iosco, MI
Built 1931 Load: 30.1 t ADT: 5,497
WHITTEMORE STREET
FairOver: TAWAS RIVER
TAWAS CITY, Iosco, MI
Built 1981 Load: 30.5 t ADT: 1,480
MONUMENT RD
FairOver: TAWAS RIVER
150 FT SE OF NUNN, Iosco, MI
Built 1981 Load: 30.8 t ADT: 4,030
RIVER ROAD
FairOver: AU SABLE RIVER
0.5 MI W OF US-23, Iosco, MI
Built 1963 Load: 32.1 t ADT: 4,920
CURTIS ROAD
FairOver: SMITH CREEK
0.1 MI W OF ALLEN ROAD, Iosco, MI
Built 1931 Load: 32.7 t ADT: 120
M-65
FairOver: BR HALE CREEK
6.0 MI N OF M-55, Iosco, MI
Built 1952 Load: 33.4 t ADT: 6,737
REA RD
FairOver: AU SABLE RIVER
6 MI W OF OSCODA (1/4 MI, Iosco, MI
Built 1957 Load: 33.4 t ADT: 1,200
MATTHEWS STREET
FairOver: TAWAS RIVER
TAWAS CITY, Iosco, MI
Built 1972 Load: 33.7 t ADT: 1,380
FIRST STREET
FairOver: TAWAS RIVER
TAWAS CITY, Iosco, MI
Built 1972 Load: 33.7 t ADT: 950
MEADOW ROAD
FairOver: DEAD CREEK
1.25 MI E OF KOBS ROAD, Iosco, MI
Built 1993 Load: 34.7 t ADT: 740
US-23
FairOver: TAWAS RIVER
IN TAWAS CITY, Iosco, MI
Built 1984 Load: 35.0 t ADT: 15,836
M-55
FairOver: TAWAS RIVER
IN TAWAS CITY, Iosco, MI
Built 1950 Load: 35.3 t ADT: 8,047
WHITTEMORE RD
FairOver: AU GRES RIVER
1.75 MI E OF WHITTEMORE, Iosco, MI
Built 1975 Load: 36.0 t ADT: 1,090
OLD STATE RD
FairOver: E BR OF AU GRES RIVER
2.25 M W OF SAND LAKE RD, Iosco, MI
Built 1977 Load: 36.0 t ADT: 720
US-23
FairOver: AU SABLE RIVER
IN AU SABLE, Iosco, MI
Built 1972 Load: 38.2 t ADT: 8,367
S BRANCH RD
FairOver: S BR OF AU SABLE RIVER
1.5 MI N OF LONG LAKE, Iosco, MI
Built 1979 Load: 38.6 t ADT: 1,100
SAND LAKE RD
FairOver: E BRANCH OF AUGRES RIVER
1.75 MI S OF MCIVOR, Iosco, MI
Built 1982 Load: 39.2 t ADT: 420
M-65
FairOver: AU SABLE RIVER
4.5 MI S OF ALCONA COL, Iosco, MI
Built 2003 Load: 39.5 t ADT: 2,497
SHERMAN RD
FairOver: SILVER CREEK
6 MI N OF M55, Iosco, MI
Built 1994 Load: 41.8 t ADT: 1,190
CARPENTER ROAD
FairOver: EAST BRANCH AUGRES RIVER
4300 FT W OF GREENWOOD RD, Iosco, MI
Built 1979 Load: 42.1 t ADT: 300
M-65
FairOver: AU GRES RIVER
1.0 MI S OF M-55, Iosco, MI
Built 1951 Load: 42.4 t ADT: 3,354
M-55
FairOver: HOPE CREEK
1.5 MI W OF M-65, Iosco, MI
Built 1928 Load: 42.4 t ADT: 2,529
TOWERLINE ROAD
FairOver: JOHNSON CREEK
0.5 MI S OF N SEC. LINE, Iosco, MI
Built 1988 Load: 42.8 t ADT: 160
KINGS CORNER
FairOver: PINE RIVER
1 MILE-EAST OF F41, Iosco, MI
Built 1981 Load: 47.3 t ADT: 1,000
ALABASTER RD
FairOver: E BR OF AU GRES RIV
0.3 MI E OF SAND LAKE RD, Iosco, MI
Built 1980 Load: 52.8 t ADT: 640
SIXTH AVENUE
FairOver: DEAD CREEK
TAWAS CITY, Iosco, MI
Built 1981 Load: 54.4 t ADT: 2,860
CURTIS ROAD
FairOver: HALE CREEK
500 FT W OF M-65, Iosco, MI
Built 1976 Load: 72.3 t ADT: 480
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.