Total bridges
183
Public highway bridges in Isabella County
County profile · official public datasets
Isabella County, MI
183 public highway bridges tracked in the FHWA National Bridge Inventory: 48.1% rated Good, 38.8% Fair, 13.1% Poor.
- 183
- Public bridges
- 48.1%
- Good condition
- 13.1%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Isabella County pairs a higher-than-median Poor-condition share among rated counties in the state with a newer average build year than the state inventory.
- 51st
- of 83 on Poor share
- 13.1%
- Poor-condition share
- 183
- public highway bridges
- 1983
- 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.
Isabella County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Isabella County ranks #51 of 83 Michigan counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 13.1%). Isabella County, Michigan contains 183 public highway bridges. Roughly 48.1% are rated “Good,” 38.8% “Fair,” and 13.1% “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
48.1%
88 of 183 rated 7-9
Fair condition
38.8%
71 of 183 rated 5-6
Poor condition
13.1%
24 of 183 rated 4 or below
In-state Poor-share rank
#51 of 83
Among Michigan counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 183 NBI-tracked bridges by lowest applicable component rating.
Good 48.1% (88)
Fair 38.8% (71)
Poor 13.1% (24)
Isabella County's Poor-condition bridges carry 41,369 vehicle crossings a day
That is 12.1% of the county's reported daily bridge traffic on 13.2% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 1,724 crossings a day against 1,314 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 182 of 183 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
42.6% of Isabella County's bridges have passed the 50-year mark
78 of the 183 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 48.1% 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 20.9% of the county's Poor-condition bridge traffic
US-127 NB over CHIPPEWA RIVER, built 1961, carries 8,658 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 24-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 41,369 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Isabella County's bridges were built
183 bridges with a recorded construction year, grouped by decade
- 1900s 1
1900–1909
1 bridges
- 1910s 2
1910–1919
2 bridges
- 1920s 1
1920–1929
1 bridges
- 1930s 13
1930–1939
13 bridges
- 1940s 1
1940–1949
1 bridges
- 1950s 1
1950–1959
1 bridges
- 1960s
1960–1969
45 bridges
- 1970s
1970–1979
23 bridges
- 1980s 14
1980–1989
14 bridges
- 1990s
1990–1999
23 bridges
- 2000s
2000–2009
25 bridges
- 2010s
2010–2019
27 bridges
- 2020s 7
2020–2029
7 bridges
What this shows Construction peaked in the 1960s, when 45 of the county's bridges still in the inventory were built, which is 24.6% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year is 1983, 7 years newer than the Michigan average of 1976.
How Isabella County compares with Michigan's closest counties by inventory size
The 5 Michigan counties nearest Isabella County in number of bridges, with their condition splits. Its 13.1% Poor share is the 5th-lowest of these 6. Its average build year of 1983 against a peer-group mean of 1976 is 7 years newer.
Showing the 5 closest of 82 Michigan counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Eaton County | 200 | 30% | 63.5% | 6.5% | 1978 |
| Huron County | 192 | 31.8% | 62% | 6.3% | 1976 |
| Isabella County (this page) | 183 | 48.1% | 38.8% | 13.1% | 1983 |
| Sanilac County | 171 | 31.6% | 58.5% | 9.9% | 1978 |
| Gratiot County | 167 | 40.7% | 47.3% | 12% | 1975 |
| Bay County | 166 | 30.1% | 53% | 16.9% | 1974 |
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 Isabella 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 Isabella County, both outside Michigan so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside MI (183 bridges here).
- St. Clair County, AL · 183 bridges
- Richmond County, GA · 183 bridges
- Marshall County, IN · 183 bridges
- Appanoose County, IA · 183 bridges
Similar average build year
Nearest mean year-built outside MI (1983 here).
- Dallas County, TX · avg 1983 · 3,230 bridges
- Bexar County, TX · avg 1983 · 2,342 bridges
- Sedgwick County, KS · avg 1983 · 1,333 bridges
- Will County, IL · avg 1983 · 649 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
All bridges (183)
DENVER RD
FairOver: COLDWATER RIVER
465 FT E OF N WOODRUFF RD, Isabella, MI
Built 1975 Load: 16.2 t ADT: 70
JORDAN ROAD
FairOver: NORTH BR CHIPPEWA RIVER
30 FT W NE COR SEC 35 T15, Isabella, MI
Built 1971 Load: 16.3 t ADT: 153
NOTTAWA ROAD
FairOver: NORTH BR CHIPPEWA RIVER
SEC 11-12 DEERFIELD TWP, Isabella, MI
Built 1937 Load: 17.4 t ADT: 185
BATTLE RD
FairOver: MCDONALD DRAIN
0.2 MI W OF LOOMIS RD, Isabella, MI
Built 1970 Load: 20.1 t ADT: 80
LOOMIS ROAD
FairOver: S BR SALT RIVER
0.4 MI N OF BEAL CITY RD, Isabella, MI
Built 1971 Load: 20.4 t ADT: 50
MERIDIAN ROAD
FairOver: NORTH BR CHIPPEWA RIVER
50 FT N SW COR SE 19 T16N, Isabella, MI
Built 1934 Load: 21.4 t ADT: 1,420
RIVER RD
FairOver: COLDWATER RIVER
0.4 MI E OF S WOODRUFF RD, Isabella, MI
Built 1964 Load: 22.4 t ADT: 1,637
ROSEBUSH ROAD
FairOver: NORTH BR CHIPPEWA RIVER
SEC 12-13 NOTTAWA TWP, Isabella, MI
Built 1937 Load: 26.4 t ADT: 123
NOTTAWA ROAD
FairOver: NORTH BR CHIPPEWA RIVER
.1 M S NE COR SEC 26 T15N, Isabella, MI
Built 1978 Load: 26.5 t ADT: 128
WALTON ROAD
FairOver: SOUTH BR PINE RIVER
ROLLAND TWP SEC 3/10, Isabella, MI
Built 1971 Load: 26.6 t ADT: 199
BATTLE ROAD
FairOver: NORTH BR CHIPPEWA RIVER
SEC 25-31 VERNON TWP, Isabella, MI
Built 1937 Load: 26.9 t ADT: 246
SHEPHERD RD
FairOver: US-127
5.7 MI N OF GRATIOT COL, Isabella, MI
Built 1964 Load: 27.5 t ADT: 2,600
ISABELLA RD
FairOver: US-127
0.7 MI N OF M-20, Isabella, MI
Built 1964 Load: 27.5 t ADT: 110
CHIPPEWA ROAD
FairOver: ONION CREEK
SEC 25-26 CHIPPEWA TWP, Isabella, MI
Built 1980 Load: 28.0 t ADT: 185
COLEMAN ROAD
FairOver: NORTH BR CHIPPEWA RIVER
VERNON TWP SEC 19/30, Isabella, MI
Built 1978 Load: 28.0 t ADT: 285
LEATON RD
FairOver: US-10
2.2 MI SE OF CLARE COL, Isabella, MI
Built 1961 Load: 28.2 t ADT: 110
VERNON ROAD
FairOver: NORTH BR SALT RIVER
0.2M W SE COR SEC 33 T16N, Isabella, MI
Built 1980 Load: 28.8 t ADT: 93
BASELINE RD
FairOver: US-127
1.1 MI N OF US-127 BR, Isabella, MI
Built 1965 Load: 29.2 t ADT: 230
MERIDIAN ROAD
FairOver: NORTH BR CHIPPEWA RIVER
SEC 31 W VERNON TWP, Isabella, MI
Built 1937 Load: 29.4 t ADT: 246
BROOMFIELD ROAD
FairOver: POTTER CREEK DRAIN
SEC 21 CHIPPEWA TWP, Isabella, MI
Built 1969 Load: 29.8 t ADT: 2,019
PICKARD ROAD
FairOver: CHIPPEWA RIVER
.26 M W SE COR SEC 7 T14N, Isabella, MI
Built 1971 Load: 29.8 t ADT: 1,616
BEAL CITY RD
FairOver: US-127
3.1 MI N OF US-127BR, Isabella, MI
Built 1964 Load: 31.4 t ADT: 230
SHEPHERD ROAD
FairOver: LITTLE SALT RIVER
0.2 M S NE COR SEC 20 T13, Isabella, MI
Built 1926 Load: 31.6 t ADT: 1,430
PLEASANT VALLEY RD
FairOver: US-127
3.1 MI N OF GRATIOT COL, Isabella, MI
Built 1964 Load: 32.1 t ADT: 345
LEATON ROAD
FairOver: NORTH BR CHIPPEWA RIVER
AT SE COR SEC 6 T14N R3W, Isabella, MI
Built 1969 Load: 32.3 t ADT: 2,516
SHEPHERD ROAD
FairOver: SPRING CREEK
SEC 20-21 DENVER TWP, Isabella, MI
Built 1980 Load: 32.6 t ADT: 160
LEATON ROAD
FairOver: LITTLE SALT RIVER
0.5 M S NW COR SEC 29 COE, Isabella, MI
Built 1970 Load: 32.7 t ADT: 181
LINCOLN ST
FairOver: CHIPPEWA RIVER CHANNEL
IN MT PLEASANT, Isabella, MI
Built 1910 Load: 32.7 t ADT: 2,161
IRR BIA RTE 12
FairOver: NEFF EXTENSION DRAIN
SAGINAW CHIPPEWA RES., Isabella, MI
Built 1998 Load: 32.7 t ADT: 60
IRR BIA RTE 11
FairOver: ONION CREEK DRAIN
SAGINAW CHIPPEWA RES., Isabella, MI
Built 1998 Load: 32.7 t ADT: 60
BROOMFIELD RD
FairOver: POTTER CREEK
200 E OF GENUINE RD, Isabella, MI
Built 1986 Load: 32.7 t ADT: 2,019
LITTLEFIELD ROAD
FairOver: CHIPPEWA RIVER
0.1 M S NE COR SEC 18 T14, Isabella, MI
Built 1971 Load: 32.9 t ADT: 213
BROADWAY ST
FairOver: CHIPPEWA RIVER
IN MT PLEASANT, Isabella, MI
Built 1910 Load: 33.3 t ADT: 2,352
VANDECAR ROAD
FairOver: SOUTH BR CHIPPEWA RIVER
SEC 22-23 DEERFIELD TWP, Isabella, MI
Built 1992 Load: 33.4 t ADT: 425
BROADWAY RD
FairOver: US-127
0.7 MI S OF M-20, Isabella, MI
Built 1965 Load: 33.7 t ADT: 6,190
GRASS LAKE RD
FairOver: US-127
2.1 MI S OF US-10, Isabella, MI
Built 1964 Load: 33.7 t ADT: 250
ISABELLA ROAD
FairOver: CHIPPEWA RIVER
0.5 M N SE COR SEC 2 T14N, Isabella, MI
Built 1972 Load: 34.1 t ADT: 1,330
SUMMERTON RD
FairOver: US-127
4.0 MI S OF M-20, Isabella, MI
Built 1965 Load: 34.3 t ADT: 160
REMUS ROAD
FairOver: ONION CREEK DRAIN
0.3 M E SW COR SEC 16 T14, Isabella, MI
Built 1975 Load: 34.3 t ADT: 620
US-127 NB
FairOver: LITTLE SALT RIVER
4.7 MI N OF GRATIOT COL, Isabella, MI
Built 1961 Load: 35.6 t ADT: 10,457
US-127 SB
FairOver: LITTLE SALT RIVER
4.7 MI N OF GRATIOT COL, Isabella, MI
Built 1961 Load: 35.6 t ADT: 10,457
BROOMFIELD RD
FairOver: US-127
2.0 MI S OF M-20, Isabella, MI
Built 1964 Load: 35.6 t ADT: 5,954
US-10
FairOver: US-10 WB RAMP
1.4 MI SE OF CLARE COL, Isabella, MI
Built 1962 Load: 35.6 t ADT: 5,688
US-127 NB
FairOver: EAST RIVER RD
0.1 MI N OF US-127 BR, Isabella, MI
Built 1961 Load: 36.0 t ADT: 8,625
US-127 BR NB
FairOver: US-127 SB
@ S JCT US-127 BR, Isabella, MI
Built 1961 Load: 36.3 t ADT: 7,675
US-127 SB
FairOver: SPRING CREEK
IN ROSEBUSH, Isabella, MI
Built 1961 Load: 36.3 t ADT: 8,152
BLANCHARD RD
FairOver: US-127
4.1 MI N OF GRATIOT COL, Isabella, MI
Built 1960 Load: 37.3 t ADT: 580
ROSEBUSH RD
FairOver: US-127
IN ROSEBUSH, Isabella, MI
Built 1961 Load: 37.3 t ADT: 3,138
MILLBROOK ROAD
FairOver: CEDAR CREEK
0.6 M E SW COR SEC 34 T14, Isabella, MI
Built 1979 Load: 38.0 t ADT: 83
COLEMAN RD
FairOver: US-127 SB
4.1 MI S OF US-10, Isabella, MI
Built 1965 Load: 38.6 t ADT: 803
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.