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.

Total bridges

163

Public highway bridges in Shiawassee County

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

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.

Source FHWA National Bridge Inventory (year built) As of 2024 NBI release

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.

Bridge inventory size and condition shares for Shiawassee County and the 5 Michigan counties closest to it in inventory size
County Bridges Poor
Gratiot County 167 12%
Bay County 166 16.9%
Livingston County 165 14.5%
Lapeer County 163 9.2%
Shiawassee County (this page) 163 9.2%
Jackson County 158 10.1%

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).

Similar average build year

Nearest mean year-built outside MI (1981 here).

Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.

All 163 Good 74 Fair 74 Poor 15

Good-condition bridges (74)

KROUSE RD

Good

Over: BEAR CREEK

3 MI SE OF OVID, Shiawassee, MI

Built 1994 Load: 14.3 t ADT: 189

SHAFTSBURG RD

Good

Over: BEAR CREEK

4.7 MI SE OF OVID, Shiawassee, MI

Built 1959 Load: 21.7 t ADT: 125

OLIVER STREET

Good

Over: SHIAWASSEE RIVER

CITY OF OWOSSO, Shiawassee, MI

Built 2007 Load: 22.0 t ADT: 9,200

VANDEKARR ROAD

Good

Over: MAPLE RIVER

3 MILES SOUTH OF OWOSSO, Shiawassee, MI

Built 1962 Load: 24.6 t ADT: 844

COOK RD

Good

Over: MAPLE RIVER

3.5 MI S OF OWOSSO, Shiawassee, MI

Built 1970 Load: 24.9 t ADT: 215

RILEY RD

Good

Over: MISTEGUAY CREEK

1.25 MI NE OF JUDDVILLE, Shiawassee, MI

Built 1983 Load: 25.6 t ADT: 88

ALLAN RD

Good

Over: MISTEGUAY CREEK

1.1 MI SE OF NEW LOTHROP, Shiawassee, MI

Built 1990 Load: 25.9 t ADT: 128

DURAND ROAD

Good

Over: RUSHBED CREEK

7 MILES NORTH OF DURAND, Shiawassee, MI

Built 1968 Load: 27.2 t ADT: 1,241

MORRICE ROAD

Good

Over: LOOKINGGLASS RIVER

2 MILES NORTH OF MORRICE, Shiawassee, MI

Built 1952 Load: 28.2 t ADT: 1,534

MASON RD

Good

Over: MIDDLEBURY COUNTY DRAIN

2.9 MI SE OF CARLAND, Shiawassee, MI

Built 2003 Load: 28.8 t ADT: 269

EXCHANGE RD

Good

Over: SHIAWASSEE RIVER

1 MI NE OF BANCROFT, Shiawassee, MI

Built 1983 Load: 28.8 t ADT: 320

BALCOM RD

Good

Over: ALDER CREEK

3.3 MI S OF OVID, Shiawassee, MI

Built 1979 Load: 29.2 t ADT: 104

ELLSWORTH RD

Good

Over: LOOKINGGLASS RIVER

3.5 MI SE OF MORRICE, Shiawassee, MI

Built 1985 Load: 30.1 t ADT: 41

REED ROAD

Good

Over: PORTER CREEK

2.3 MI SW OF NEW LOTHROP, Shiawassee, MI

Built 1981 Load: 30.1 t ADT: 105

COLBY LAKE RD

Good

Over: LOOKINGGLASS RIVER

2.2 MI SE OF LAINGSBURG, Shiawassee, MI

Built 1984 Load: 30.5 t ADT: 346

SHAFTSBURG ROAD

Good

Over: S BR LOOKINGGLASS RIVER

1 MI SOUTH OF SHAFTSBURG, Shiawassee, MI

Built 1994 Load: 30.8 t ADT: 645

GALE RD

Good

Over: LOOKINGGLASS RIVER

5 MI SE OF BENNINGTON, Shiawassee, MI

Built 1989 Load: 31.1 t ADT: 126

COUNTY LINE RD

Good

Over: JONES CREEK

3.5 MI S OF LENNON, Shiawassee, MI

Built 1989 Load: 32.1 t ADT: 424

JUDDVILLE ROAD

Good

Over: SHIAWASSEE RIVER

3 MILES NORTH OF OWOSSO, Shiawassee, MI

Built 2009 Load: 32.7 t ADT: 1,975

TYRRELL RD

Good

Over: LOOKINGGLASS RIVER

3.7 MI W OF BANCROFT, Shiawassee, MI

Built 1961 Load: 32.7 t ADT: 170

BRADEN RD

Good

Over: S BR LOOKINGGLASS RIVER

1 MI S OF SHAFTSBURG, Shiawassee, MI

Built 2005 Load: 33.4 t ADT: 449

STATE ROAD

Good

Over: SIX MILE CR/STEWART DRN

3.5 MILES N OF CORUNNA, Shiawassee, MI

Built 2010 Load: 33.7 t ADT: 1,917

MIDDLETON RD

Good

Over: RUSHBED CREEK

2.5 MI S OF JUDDVILLE, Shiawassee, MI

Built 1985 Load: 33.7 t ADT: 385

I-69 EB

Good

Over: WEBB DRAIN

2.7 MI SW OF GENESEE COL, Shiawassee, MI

Built 1961 Load: 34.0 t ADT: 14,378

BALCOM RD

Good

Over: ALDER CREEK

2 MI S OF OVID, Shiawassee, MI

Built 1976 Load: 35.0 t ADT: 65

JOHNSTONE RD

Good

Over: SHIAWASSEE RIVER

3.25 MI NE OF HENDERSON, Shiawassee, MI

Built 1986 Load: 35.6 t ADT: 798

BALDWIN ROAD

Good

Over: MAPLE RIVER

1MISM21&5 5MI WOFINTERM21, Shiawassee, MI

Built 1984 Load: 36.0 t ADT: 1,142

BALDWIN RD

Good

Over: BEAR CREEK

2 MI NW OF BENNINGTON, Shiawassee, MI

Built 1969 Load: 36.0 t ADT: 312

STATE RD

Good

Over: LOOKINGGLASS RIVER

3.4 MI NE OF MORRICE, Shiawassee, MI

Built 2001 Load: 36.6 t ADT: 238

NEW LOTHROP RD

Good

Over: MISTEGUAY CREEK

4.3 MI S OF NEW LOTHROP, Shiawassee, MI

Built 2005 Load: 36.9 t ADT: 351

OLD M-78

Good

Over: VERMILLION CREEK

1.3 MI NE OF CLINTON COL, Shiawassee, MI

Built 2009 Load: 37.3 t ADT: 4,397

BEARDSLEE RD

Good

Over: LOOKINGGLASS RIVER

4.5 MI SE OF LAINGSBURG, Shiawassee, MI

Built 1984 Load: 38.9 t ADT: 210

JUDDVILLE ROAD

Good

Over: PORTER CREEK

7 MI NORTHEAST OF OWOSSO, Shiawassee, MI

Built 1998 Load: 39.2 t ADT: 1,414

CRONK RD

Good

Over: MISTEGUAY CREEK DRAIN

1.3 MI SE OF JUDDVILLE, Shiawassee, MI

Built 1991 Load: 39.2 t ADT: 203

BEARDSLEE RD

Good

Over: S BR LOOKINGGLASS RIVER

1.5 MI SE OF SHAFTSBURG, Shiawassee, MI

Built 1983 Load: 39.2 t ADT: 523

M-21

Good

Over: LIMBARG COUNTY DRAIN

1.6 MI W OF GENESEE COL, Shiawassee, MI

Built 2009 Load: 39.5 t ADT: 8,200

M-21

Good

Over: LEWIS DRAIN

1.4 MI E OF CLINTON COL, Shiawassee, MI

Built 1998 Load: 40.5 t ADT: 6,438

REED RD

Good

Over: HOLLY DRAIN

1.2 MI SE OF VERNON, Shiawassee, MI

Built 1994 Load: 40.5 t ADT: 179

PARMENTER RD

Good

Over: SHIAWASSEE RIVER

0.5 MI NW OF VERNON, Shiawassee, MI

Built 2000 Load: 40.8 t ADT: 359

COLE RD

Good

Over: SHIAWASSEE RIVER

2 MI SE OF BANCROFT, Shiawassee, MI

Built 1988 Load: 41.5 t ADT: 936

MONROE RD

Good

Over: THREE MILE CREEK

0.5 MI N 1 MI E OF DURAND, Shiawassee, MI

Built 1986 Load: 41.8 t ADT: 363

LANSING ROAD

Good

Over: SHIAWASSEE RIVER

1.5 MI NE OF BANCROFT, Shiawassee, MI

Built 1989 Load: 42.1 t ADT: 2,699

SAGINAW ST

Good

Over: PORTER CREEK

IN NEW LOTHROP, Shiawassee, MI

Built 2003 Load: 42.7 t ADT: 1,178

CORK RD

Good

Over: LOOKINGGLASS RIVER

4.5 MI W OF BANCROFT, Shiawassee, MI

Built 1985 Load: 42.8 t ADT: 78

WARNER RD

Good

Over: S BR LOOKINGGLASS RIVER

1 MI SW OF SHAFTSBURG, Shiawassee, MI

Built 2001 Load: 43.7 t ADT: 510

M-21

Good

Over: RUSH CREEK

2.8 MI W OF GENESEE COL, Shiawassee, MI

Built 2022 Load: 44.4 t ADT: 9,700

WOODBURY ROAD

Good

Over: LOOKINGGLASS RIVER

2 MILES S OF LAINGSBURG, Shiawassee, MI

Built 1997 Load: 45.0 t ADT: 3,231

BINGHAM RD

Good

Over: NORTH STATE DRAIN

0.15 MI N OF HENDERSON, Shiawassee, MI

Built 2006 Load: 45.0 t ADT: 216

M-21

Good

Over: CRAWFORD DRAIN

0.6 MI W OF GENESEE COL, Shiawassee, MI

Built 2009 Load: 45.4 t ADT: 8,200

LANSING ROAD

Good

Over: LOOKINGGLASS RIVER

3 MI SW OF BANCROFT, Shiawassee, MI

Built 2007 Load: 45.4 t ADT: 2,568

Read our methodology - how this data is sourced, computed, and verified.

Related

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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.