Total bridges
163
Public highway bridges in Shiawassee County
County profile · official public datasets
Shiawassee County, MI
163 public highway bridges tracked in the FHWA National Bridge Inventory: 45.4% rated Good, 45.4% Fair, 9.2% Poor.
- 163
- Public bridges
- 45.4%
- Good condition
- 9.2%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Shiawassee 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 45%
- lowest Poor share in state
- 9.2%
- Poor-condition share
- 163
- public highway bridges
- 1981
- 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.
Shiawassee County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Shiawassee County ranks #37 of 83 Michigan counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 9.2%). Shiawassee County, Michigan contains 163 public highway bridges. Roughly 45.4% are rated “Good,” 45.4% “Fair,” and 9.2% “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
45.4%
74 of 163 rated 7-9
Fair condition
45.4%
74 of 163 rated 5-6
Poor condition
9.2%
15 of 163 rated 4 or below
In-state Poor-share rank
#37 of 83
Among Michigan counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 163 NBI-tracked bridges by lowest applicable component rating.
Good 45.4% (74)
Fair 45.4% (74)
Poor 9.2% (15)
Shiawassee County's Poor-condition bridges carry 52,246 vehicle crossings a day
That is 3.8% of the county's reported daily bridge traffic on 9.2% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 3,483 crossings a day against 1,976 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 163 of 163 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
38% of Shiawassee County's bridges have passed the 50-year mark
62 of the 163 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 45.4% 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 27.5% of the county's Poor-condition bridge traffic
I-69 EB over HURON & EASTERN RR, built 1961, carries 14,378 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 15-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 52,246 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Shiawassee County's bridges were built
163 bridges with a recorded construction year, grouped by decade
- 1900s 1
1900–1909
1 bridges
- 1920s 2
1920–1929
2 bridges
- 1930s 5
1930–1939
5 bridges
- 1940s 2
1940–1949
2 bridges
- 1950s 6
1950–1959
6 bridges
- 1960s
1960–1969
39 bridges
- 1970s 11
1970–1979
11 bridges
- 1980s
1980–1989
34 bridges
- 1990s
1990–1999
29 bridges
- 2000s
2000–2009
24 bridges
- 2010s 7
2010–2019
7 bridges
- 2020s 3
2020–2029
3 bridges
What this shows Construction peaked in the 1960s, when 39 of the county's bridges still in the inventory were built, which is 23.9% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year is 1981, 5 years newer than the Michigan average of 1976.
How Shiawassee County compares with Michigan's closest counties by inventory size
The 5 Michigan counties nearest Shiawassee County in number of bridges, with their condition splits. Its 9.2% Poor share is the 2nd-lowest of these 6. Its average build year of 1981 against a peer-group mean of 1977 is in line with the group.
Showing the 5 closest of 82 Michigan counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Gratiot County | 167 | 40.7% | 47.3% | 12% | 1975 |
| Bay County | 166 | 30.1% | 53% | 16.9% | 1974 |
| Livingston County | 165 | 26.7% | 58.8% | 14.5% | 1974 |
| Lapeer County | 163 | 36.2% | 54.6% | 9.2% | 1982 |
| Shiawassee County (this page) | 163 | 45.4% | 45.4% | 9.2% | 1981 |
| Jackson County | 158 | 34.2% | 55.7% | 10.1% | 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 Shiawassee 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 Shiawassee County, both outside Michigan so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside MI (163 bridges here).
- Mercer County, IL · 163 bridges
- Jennings County, IN · 163 bridges
- Wayne County, IA · 163 bridges
- Jackson County, LA · 163 bridges
Similar average build year
Nearest mean year-built outside MI (1981 here).
- Franklin County, OH · avg 1981 · 922 bridges
- Greenville County, SC · avg 1981 · 635 bridges
- Montgomery County, OH · avg 1981 · 632 bridges
- McLean County, IL · avg 1981 · 624 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Fair-condition bridges (74)
M-52
FairOver: SHIAWASSEE RIVER
2.7 MI S OF SAGINAW COL, Shiawassee, MI
Built 1999 Load: 2.6 t ADT: 5,281
HIBBARD ROAD
FairOver: BURGESS DRAIN
1.3 M NE OF BENNINGTON, Shiawassee, MI
Built 1968 Load: 14.3 t ADT: 1,137
TYRRELL RD
FairOver: AUSTIN CREEK
3 MI N & .3 MI E OF PERRY, Shiawassee, MI
Built 1965 Load: 14.3 t ADT: 271
DURAND ROAD
FairOver: PORTER CREEK
1 MILES S.W. OF NEW LOTHR, Shiawassee, MI
Built 1956 Load: 18.8 t ADT: 1,789
NEW LOTHROP RD
FairOver: HOLLY DRAIN
1 MI E 0.7 MI N OF DURAND, Shiawassee, MI
Built 1971 Load: 20.1 t ADT: 1,850
M-52
FairOver: LOOKING GLASS RIVER
2.6 MI N OF I-69, Shiawassee, MI
Built 2000 Load: 21.4 t ADT: 10,212
GENESEE ST
FairOver: MISTEGUAY CREEK
IN NEW LOTHROP, Shiawassee, MI
Built 1947 Load: 21.7 t ADT: 2,477
LANSING ROAD
FairOver: WEBB CREEK DRAIN
3 MILES NE OF DURAND, Shiawassee, MI
Built 1994 Load: 22.4 t ADT: 6,033
LAINGSBURG RD
FairOver: LOOKINGGLASS RIVER
0.75 MI S OF LAINGSBURG, Shiawassee, MI
Built 1961 Load: 22.7 t ADT: 357
VERNON ROAD
FairOver: WEBB CREEK
1 MILE NORTH OF VERNON, Shiawassee, MI
Built 1966 Load: 25.6 t ADT: 811
FENNER ROAD
FairOver: LOOKINGGLASS RIVER
3 MI SE OF LAINGSBURG, Shiawassee, MI
Built 1962 Load: 25.9 t ADT: 680
WINEGAR RD
FairOver: LOOKINGGLASS RIVER
3.5 MI NE OF MORRICE, Shiawassee, MI
Built 1963 Load: 26.2 t ADT: 223
RUESS ROAD
FairOver: MAPLE RIVER
3 MI SW OF OWOSSO, Shiawassee, MI
Built 1963 Load: 28.2 t ADT: 910
JUDDVILLE ROAD
FairOver: MISTEGUAY CREEK
4 MI S OF NEW LOTHROP, Shiawassee, MI
Built 1944 Load: 28.5 t ADT: 1,320
RILEY RD
FairOver: PORTER CREEK
3.25 MI NW OF JUDDVILLE, Shiawassee, MI
Built 1971 Load: 29.2 t ADT: 130
WARREN RD
FairOver: MAPLE RIVER
1.6 MI SE OF OVID, Shiawassee, MI
Built 1959 Load: 29.2 t ADT: 1,202
LANSING ROAD
FairOver: HOLLY DRAIN
0.5 MI NE OF DURAND, Shiawassee, MI
Built 1988 Load: 29.8 t ADT: 6,858
MORRICE ROAD
FairOver: MAPLE RIVER
7 MILES NORTH OF MORRICE, Shiawassee, MI
Built 1956 Load: 29.8 t ADT: 1,662
DEWEY ROAD
FairOver: MAPLE RIVER
3 MI W & 2 MI S OF OWOSSO, Shiawassee, MI
Built 1980 Load: 31.4 t ADT: 249
DURAND RD
FairOver: I-69
0.8 MI NE OF M-71, Shiawassee, MI
Built 1961 Load: 32.7 t ADT: 2,882
I-69 WB
FairOver: HURON & EASTERN RR
1.2 MI SW OF GENESEE COL, Shiawassee, MI
Built 1961 Load: 33.4 t ADT: 14,378
GRAND RIVER RD
FairOver: I-69
7.8 MI NE OF M-52, Shiawassee, MI
Built 1961 Load: 33.4 t ADT: 2,396
VERNON ROAD
FairOver: NORTHWOOD DRAIN
HAZELTON TWP SEC 5 6, Shiawassee, MI
Built 1970 Load: 33.4 t ADT: 120
M-52
FairOver: SHIAWASSEE RIVER
IN OWOSSO, Shiawassee, MI
Built 2004 Load: 35.0 t ADT: 11,489
BATH ROAD
FairOver: ROWLEY CREEK
3 MILES WEST OF BYRON, Shiawassee, MI
Built 1900 Load: 35.3 t ADT: 733
HENDERSON ROAD
FairOver: SHIAWASSEE RIVER
5 MILES NORTH OF OWOSSO, Shiawassee, MI
Built 1990 Load: 35.3 t ADT: 870
I-69 WB
FairOver: WEBB DRAIN
2.7 MI SW OF GENESEE COL, Shiawassee, MI
Built 1961 Load: 35.6 t ADT: 14,378
I-69 EB
FairOver: SHAFTSBURG RD
1.6 MI E OF COLBY LAKE RD, Shiawassee, MI
Built 1989 Load: 35.6 t ADT: 20,138
WALNUT STREET
FairOver: HOLLY DRAIN
IN THE VILLAGE OF VERNON, Shiawassee, MI
Built 1987 Load: 36.0 t ADT: 90
M-71
FairOver: SHIAWASSEE RIVER
IN OWOSSO, Shiawassee, MI
Built 1983 Load: 36.3 t ADT: 8,752
NEW LOTHROP RD
FairOver: MISTEGUAY CREEK
2.1 MI S OF NEW LOTHROP, Shiawassee, MI
Built 1992 Load: 36.3 t ADT: 342
M-52
FairOver: MAPLE RIVER
4.0 MI SW OF M-21, Shiawassee, MI
Built 1969 Load: 36.9 t ADT: 9,501
STATE RD
FairOver: I-69
5.8 MI NE OF M-52, Shiawassee, MI
Built 1966 Load: 37.3 t ADT: 1,236
I-69 WB
FairOver: SHAFTSBURG RD
1.6 MI E OF COLBY LAKE RD, Shiawassee, MI
Built 1989 Load: 37.3 t ADT: 20,138
I-69 WB
FairOver: BATH RD
2.5 MILES W OF PERRY, Shiawassee, MI
Built 1988 Load: 37.6 t ADT: 20,138
M-21
FairOver: SHIAWASSEE RIVER
IN OWOSSO, Shiawassee, MI
Built 1970 Load: 37.6 t ADT: 22,689
BYRON RD
FairOver: MISTEGUAY CREEK
2.4 MI SE OF JUDDVILLE, Shiawassee, MI
Built 1996 Load: 38.6 t ADT: 92
I-69 EB
FairOver: LOOKING GLASS RIVER
5.0 MI NE OF M-52, Shiawassee, MI
Built 1961 Load: 39.2 t ADT: 192,000
I-69 WB
FairOver: LOOKING GLASS RIVER
5.0 MI NE OF M-52, Shiawassee, MI
Built 1961 Load: 39.2 t ADT: 192,000
LANSING ROAD
FairOver: GTW RR & GARRISON RD
1 MILE NW OF DURAND, Shiawassee, MI
Built 1992 Load: 39.2 t ADT: 3,723
I-69 EB
FairOver: BATH RD
2.5 MI WEST OF PERRY, Shiawassee, MI
Built 1988 Load: 39.5 t ADT: 20,138
WOODBURY RD
FairOver: I-69
0.6 M E OF CLINTON COL, Shiawassee, MI
Built 1989 Load: 39.9 t ADT: 2,945
NEWBURG ROAD
FairOver: THREE MILE CREEK
0.5 MILE EAST OF DURAND, Shiawassee, MI
Built 1935 Load: 39.9 t ADT: 2,548
WOODBURY ROAD
FairOver: S BR LOOKINGGLASS RIVER
5.5 MILES S OF LAINGSBURG, Shiawassee, MI
Built 1990 Load: 40.5 t ADT: 4,809
I-69 WB
FairOver: COLBY LAKE RD
1.5 MI W OF SHAFTSBURG, Shiawassee, MI
Built 1989 Load: 41.8 t ADT: 20,138
I-69 EB
FairOver: COLBY LAKE RD
1.5 MI W OF SHAFTSBURG, Shiawassee, MI
Built 1989 Load: 42.1 t ADT: 20,138
I-69 WB
FairOver: VERMILLION CREEK
1.5 MI E CLINTON CO LINE, Shiawassee, MI
Built 1989 Load: 43.4 t ADT: 20,138
GOODALL RD
FairOver: I-69
2.7 MI SW OF GENESEE COL, Shiawassee, MI
Built 1961 Load: 43.7 t ADT: 250
BRITTON RD
FairOver: I-69
0.5 M WEST OF PERRY, Shiawassee, MI
Built 1989 Load: 43.7 t ADT: 25,000
BENNINGTON RD
FairOver: WEBB CREEK
2 MI S .6 MI W OF LENNON, Shiawassee, MI
Built 1997 Load: 44.1 t ADT: 128
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.