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)
WEIDMAN ROAD
GoodOver: LEWIS DRAIN
0.6 MI W OF MISSION ROAD, Isabella, MI
Built 2014 Load: 34.7 t ADT: 3,530
ISABELLA ROAD
GoodOver: LITTLE SALT RIVER
0.6 M S NE COR SEC 35 T13, Isabella, MI
Built 1993 Load: 34.8 t ADT: 686
REMICK ROAD
GoodOver: PINE RIVER
SEC 36C ROLLAND TWP, Isabella, MI
Built 1985 Load: 35.8 t ADT: 120
MISSION ROAD
GoodOver: ANN ARBOR RAILROAD
0.1M N SE COR SEC 27 T14N, Isabella, MI
Built 2005 Load: 37.8 t ADT: 9,200
COE RD
GoodOver: US-127
1.0 MI N OF GRATIOT COL, Isabella, MI
Built 1965 Load: 40.5 t ADT: 300
PLEASANT VALLEY RD
GoodOver: LITTLE SALT RIVER
SEC 16-21 COE TWP, Isabella, MI
Built 1989 Load: 41.3 t ADT: 511
ROSEBUSH ROAD
GoodOver: NORTH BR SALT RIVER
0.5M E NWCOR SEC15 DENV, Isabella, MI
Built 2017 Load: 42.1 t ADT: 885
SHEPHERD ROAD
GoodOver: POTTER CREEK
0.02M S NE COR SEC 32 T14, Isabella, MI
Built 1998 Load: 42.5 t ADT: 2,402
ISABELLA ROAD
GoodOver: SPRING CREEK
.28 M S NE COR SEC 14 T15, Isabella, MI
Built 1978 Load: 42.8 t ADT: 192
US-127 SB
GoodOver: US-10 BR
@ US-10, Isabella, MI
Built 2006 Load: 43.4 t ADT: 6,302
BROOMFIELD ROAD
GoodOver: ONION CREEK
SEC 23-26 CHIPPEWA TWP, Isabella, MI
Built 1992 Load: 43.6 t ADT: 236
BEAL CITY ROAD
GoodOver: JORDAN CREEK
0.5 MILE E OF LEATON RD, Isabella, MI
Built 1978 Load: 43.6 t ADT: 210
SHEPHERD ROAD
GoodOver: CHIPPEWA RIVER
.35 M S NE COR SEC 8 T14N, Isabella, MI
Built 1993 Load: 43.7 t ADT: 826
US-127 NB
GoodOver: US-10 BR
@ US-10, Isabella, MI
Built 2006 Load: 44.4 t ADT: 6,302
LOOMIS RD
GoodOver: N BR SALT RIVER
900 FT S OF BATTLE RD, Isabella, MI
Built 2021 Load: 44.4 t ADT: 423
WEIDMAN ROAD
GoodOver: LEWIS DRAIN
0.2 MI E OF MISSION ROAD, Isabella, MI
Built 2019 Load: 44.7 t ADT: 198
WEIDMAN ROAD
GoodOver: LEWIS DRAIN
0.1 MI E OF ISABELLA ROAD, Isabella, MI
Built 2014 Load: 44.7 t ADT: 196
M-20
GoodOver: CHIPPEWA RIVER
IN MT PLEASANT, Isabella, MI
Built 1996 Load: 45.0 t ADT: 10,842
WISE ROAD
GoodOver: LITTLE SALT RIVER
0.2 M N SE COR SEC 10 T13, Isabella, MI
Built 2010 Load: 47.2 t ADT: 1,548
JORDAN ROAD
GoodOver: COLDWATER RIVER
SEC 30-31 NOTTAWA TWP, Isabella, MI
Built 2013 Load: 47.3 t ADT: 614
BEAL CITY ROAD
GoodOver: NORTH BR CHIPPEWA RIVER
.15 M E NW COR SEC 25 T15, Isabella, MI
Built 2013 Load: 47.3 t ADT: 645
FREMONT ROAD
GoodOver: LITTLE SALT RIVER
.25 M W NE COR SEC 29 T13, Isabella, MI
Built 2007 Load: 47.7 t ADT: 242
CHIPPEWA ROAD
GoodOver: NORTH BR SALT RIVER
SEC 13-14 DENVER TWP, Isabella, MI
Built 1991 Load: 47.7 t ADT: 121
SUMMERTON ROAD
GoodOver: LITTLE SALT RIVER
0.5 MI S OF COE RD, Isabella, MI
Built 2007 Load: 47.7 t ADT: 45
WEIDMAN ROAD
GoodOver: NORTH BR CHIPPEWA RIVER
0.4M E NW COR SEC 24 T15N, Isabella, MI
Built 2000 Load: 49.1 t ADT: 1,275
LEATON ROAD
GoodOver: LEWIS DRAIN
0.4M N SE COR SEC 19 T15N, Isabella, MI
Built 2014 Load: 49.9 t ADT: 1,308
LEATON ROAD
GoodOver: SPRING CREEK
0.1M N SE COR SEC 18 T15N, Isabella, MI
Built 2014 Load: 49.9 t ADT: 1,308
BRIDGE STREET
GoodOver: COLDWATER RIVER
SEC 18C NOTTAWA TWP, Isabella, MI
Built 1998 Load: 50.4 t ADT: 107
BASELINE ROAD
GoodOver: NORTH BR CHIPPEWA RIVER
.1 M W SE COR SEC 35 T15N, Isabella, MI
Built 2006 Load: 52.7 t ADT: 427
BRINTON ROAD
GoodOver: NORTH BRANCH PINE RIVER
ROLLAND TWP SEC 14 & 15, Isabella, MI
Built 1999 Load: 52.7 t ADT: 270
BEAL CITY ROAD
GoodOver: S BR SALT RIVER
0.8 MILE E OF LEATON RD, Isabella, MI
Built 2011 Load: 53.1 t ADT: 111
BROOMFIELD ROAD
GoodOver: SOUTH BR CHIPPEWA RIVER
SEC 20-29 DEERFIELD TWP, Isabella, MI
Built 1995 Load: 53.4 t ADT: 382
CHIPPEWA ROAD
GoodOver: LITTLE SALT RIVER
SEC 1-2 COE TWP, Isabella, MI
Built 2008 Load: 54.1 t ADT: 72
ROLLAND ROAD
GoodOver: PINE RIVER
0.3N SE COR SEC 4 T13N R6, Isabella, MI
Built 2008 Load: 54.3 t ADT: 535
COLEMAN ROAD
GoodOver: MCDONALD DRAIN
100 FT E NW SEC 29 T16N R, Isabella, MI
Built 2013 Load: 54.8 t ADT: 693
PICKARD ROAD
GoodOver: NORTH BR CHIPPEWA RIVER
SEC 12-13 DEERFIELD TWP, Isabella, MI
Built 2019 Load: 55.1 t ADT: 4,252
REMUS ROAD
GoodOver: ONION CREEK
400 FT E OF WISE ROAD, Isabella, MI
Built 2019 Load: 55.7 t ADT: 101
BEAL CITY ROAD
GoodOver: SOUTH BR SALT RIVER
0.8 MILE E OF LOOMIS RD, Isabella, MI
Built 2021 Load: 56.4 t ADT: 88
BEAL CITY ROAD
GoodOver: JORDAN CREEK
SEC 21-28 DENVER TWP, Isabella, MI
Built 2007 Load: 56.9 t ADT: 95
DEERFIELD ROAD
GoodOver: POTTER CREEK
SEC 27-34 CHIPPEWA TWP, Isabella, MI
Built 1983 Load: 57.3 t ADT: 175
BEAL CITY ROAD
GoodOver: SOUTH BR SALT RIVER
0.5 MILE E OF LOOMIS RD, Isabella, MI
Built 2021 Load: 58.6 t ADT: 88
SHEPHERD ROAD
GoodOver: JORDON CREEK
400 FT S BEAL CITY ROAD, Isabella, MI
Built 2019 Load: 58.6 t ADT: 100
LINCOLN ROAD
GoodOver: CHIPPEWA RIVER
0.1M N SW COR SEC 21 T14N, Isabella, MI
Built 2017 Load: 59.6 t ADT: 6,666
MERIDIAN ROAD
GoodOver: NORTH BR CHIPPEWA RIVER
SEC 19W UNION TWP, Isabella, MI
Built 2018 Load: 59.6 t ADT: 1,533
ISABELLA ROAD
GoodOver: LITTLE SALT RIVER
0.3 M N SW COR SEC 25 T13, Isabella, MI
Built 2018 Load: 59.9 t ADT: 762
MERIDIAN ROAD
GoodOver: SOUTH BR CHIPPEWA RIVER
SEC 30W UNION TWP, Isabella, MI
Built 2003 Load: 61.0 t ADT: 1,277
WISE RD
GoodOver: ONION CREEK
200 FT N OF REMUS RD, Isabella, MI
Built 2018 Load: 61.2 t ADT: 1,658
DREW ROAD
GoodOver: SOUTH BR CHIPPEWA RIVER
0.2 M WE 25COR SEC 28 T15, Isabella, MI
Built 2004 Load: 61.6 t ADT: 1,771
LOOMIS ROAD
GoodOver: ONION CREEK
0.32 MI N REMUS ROAD, Isabella, MI
Built 2019 Load: 61.6 t ADT: 528
ISABELLA ROAD
GoodOver: LITTLE SALT RIVER
0.1 MS NW SEC 25 LINCOLN, Isabella, MI
Built 2017 Load: 61.9 t ADT: 645
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.