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.
Good-condition bridges (74)
DURAND ROAD
GoodOver: WEBB CREEK
2.5 MILES NORTH OF DURAND, Shiawassee, MI
Built 1965 Load: 46.0 t ADT: 3,203
REED RD
GoodOver: WEBB CREEK
1.9 MI NE OF VERNON, Shiawassee, MI
Built 1995 Load: 46.0 t ADT: 47
GOODALL RD
GoodOver: SHIAWASSEE RIVER
1 MI N 0.3 MI W OF VERNON, Shiawassee, MI
Built 1989 Load: 46.0 t ADT: 352
GOULD STREET
GoodOver: SHIAWASSEE RIVER
IN OWOSSO, Shiawassee, MI
Built 1978 Load: 46.0 t ADT: 6,426
ALLAN RD
GoodOver: PORTER CREEK
1.5 MI SW OF NEW LOTHROP, Shiawassee, MI
Built 2003 Load: 46.7 t ADT: 180
M-71
GoodOver: I-69
@ M-71, Shiawassee, MI
Built 2011 Load: 47.6 t ADT: 8,100
M-71
GoodOver: HOLLY DRAIN
0.3 MI NW OF I-69, Shiawassee, MI
Built 1961 Load: 48.3 t ADT: 8,100
GOODALL RD
GoodOver: WEBB CREEK
3.25 MI NE OF DURAND, Shiawassee, MI
Built 2018 Load: 48.3 t ADT: 4,142
LENNON ROAD
GoodOver: RUSH BED CREEK
VENICE TWP SEC 21, Shiawassee, MI
Built 2012 Load: 48.6 t ADT: 304
COUNTY LINE RD
GoodOver: WEBB CREEK
3.3 MI S OF LENNON, Shiawassee, MI
Built 1994 Load: 48.9 t ADT: 367
BEARD RD
GoodOver: NEAL DRAIN
0.1 MI EAST OF BLIVEN RD, Shiawassee, MI
Built 2007 Load: 49.2 t ADT: 927
DURAND ROAD
GoodOver: RUSHBED CREEK
8 MILES NORTH OF DURAND, Shiawassee, MI
Built 2022 Load: 49.9 t ADT: 1,091
BRITTON ROAD
GoodOver: LOOKINGGLASS RIVER
3 MILES EAST OF MORRICE, Shiawassee, MI
Built 2001 Load: 50.2 t ADT: 844
STATE ROAD
GoodOver: MAPLE RIVER
2 MILES SOUTH OF CORUNNA, Shiawassee, MI
Built 1995 Load: 51.8 t ADT: 4,360
NEWBURG ROAD
GoodOver: SHIAWASSEE RIVER
2.2 MI N OF BANCROFT, Shiawassee, MI
Built 1999 Load: 55.4 t ADT: 1,140
HIBBARD ROAD
GoodOver: ALDER CREEK
3 MILES SOUTH OVID, Shiawassee, MI
Built 2000 Load: 55.7 t ADT: 526
AUSTIN RD
GoodOver: MAPLE RIVER
3 MI E & 1 MI S OF OVID, Shiawassee, MI
Built 2023 Load: 56.1 t ADT: 173
SHIAWASSEE STREET
GoodOver: SHIAWASSEE RIVER
IN THE CITY OF CORUNNA, Shiawassee, MI
Built 2003 Load: 56.4 t ADT: 13,480
SHAFTSBURG ROAD
GoodOver: BEAR CREEK
4 MILES SOUTHEAST OF OVID, Shiawassee, MI
Built 2011 Load: 58.0 t ADT: 299
SEYMOUR ROAD
GoodOver: SIX MILE CREEK
5.5 MILES NORTH OF OWOSSO, Shiawassee, MI
Built 2010 Load: 59.0 t ADT: 347
COPAS RD
GoodOver: RUSHBED CREEK
3 MI S OF JUDDVILLE, Shiawassee, MI
Built 1996 Load: 61.9 t ADT: 178
MONROE RD
GoodOver: MIKAN DRAIN
1.5 MI NE OF DURAND, Shiawassee, MI
Built 1996 Load: 61.9 t ADT: 155
NEW LOTHROP RD
GoodOver: THREE MILE CREEK
1 MI E 0.4 MI N OF DURAND, Shiawassee, MI
Built 1992 Load: 61.9 t ADT: 1,126
HIBBARD ROAD
GoodOver: BEAR CREEK
3.4 M NW OF BENNINGTON, Shiawassee, MI
Built 2011 Load: 62.5 t ADT: 649
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.