County profile · official public datasets

Calhoun County, MI

213 public highway bridges tracked in the FHWA National Bridge Inventory: 18.3% rated Good, 63.4% Fair, 18.3% Poor.

213
Public bridges: 18.3%
Good condition: 18.3%
Poor condition

The verdict

According to the Federal Highway Administration's 2024 National Bridge Inventory.

Calhoun County pairs a higher-than-median Poor-condition share among rated counties in the state with an older average build year than the state inventory.

71st
of 83 on Poor share: 18.3%
Poor-condition share: 213
public highway bridges: 1971
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.

Calhoun County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Calhoun County ranks #71 of 83 Michigan counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 18.3%). Calhoun County, Michigan contains 213 public highway bridges. Roughly 18.3% are rated “Good,” 63.4% “Fair,” and 18.3% “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

213

Public highway bridges in Calhoun County

Good condition

18.3%

39 of 213 rated 7-9

Fair condition

63.4%

135 of 213 rated 5-6

Poor condition

18.3%

39 of 213 rated 4 or below

In-state Poor-share rank

#71 of 83

Among Michigan counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 213 NBI-tracked bridges by lowest applicable component rating.

Good

18.3% (39)

Fair

63.4% (135)

Poor

18.3% (39)

Calhoun County's Poor-condition bridges carry 129,551 vehicle crossings a day

That is 9.2% of the county's reported daily bridge traffic on 18.5% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 3,322 crossings a day against 6,555 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 211 of 213 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

66.2% of Calhoun County's bridges have passed the 50-year mark

141 of the 213 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 18.3% 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 17.3% of the county's Poor-condition bridge traffic

I-94 EB over 6 1/2 MILE ROAD, built 1959, carries 22,400 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 39-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 129,551 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

pre-1900

1
1900s

3
1910s

4
1920s

9
1930s

7
1940s

5
1950s

18
1960s

78
1970s

20
1980s

18
1990s

15
2000s

11
2010s

19
2020s

5

What this shows Construction peaked in the 1960s, when 78 of the county's bridges still in the inventory were built, which is 36.6% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year is 1971, 5 years older than the Michigan average of 1976.

How Calhoun County compares with Michigan's closest counties by inventory size

The 5 Michigan counties nearest Calhoun County in number of bridges, with their condition splits. Its 18.3% Poor share is the 6th-lowest of these 6. Its average build year of 1971 against a peer-group mean of 1976 is 5 years older.

Showing the 5 closest of 82 Michigan counties eligible for comparison.

Bridge inventory size and condition shares for Calhoun County and the 5 Michigan counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Ingham County	241	15.8%	68.9%	15.4%	1972
Lenawee County	225	47.6%	39.6%	12.9%	1981
Clinton County	216	14.8%	69.4%	15.7%	1975
Calhoun County (this page)	213	18.3%	63.4%	18.3%	1971
Eaton County	200	30%	63.5%	6.5%	1978
Huron County	192	31.8%	62%	6.3%	1976

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 Calhoun 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 Calhoun County, both outside Michigan so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside MI (213 bridges here).

Bonneville County, ID · 213 bridges
Floyd County, IA · 213 bridges
Alcorn County, MS · 213 bridges
Calhoun County, MS · 213 bridges

Similar average build year

Nearest mean year-built outside MI (1971 here).

Baltimore County, MD · avg 1971 · 783 bridges
Washington County, PA · avg 1971 · 655 bridges
Linn County, OR · avg 1971 · 566 bridges
Monmouth County, NJ · avg 1971 · 505 bridges

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

All 213 Good 39 Fair 135 Poor 39

Fair-condition bridges (135)

Sort:

Calhoun County Bridge Snapshot

Condition distribution

Calhoun County's Poor-condition bridges carry 129,551 vehicle crossings a day

66.2% of Calhoun County's bridges have passed the 50-year mark

One structure carries 17.3% of the county's Poor-condition bridge traffic

How Calhoun County compares with Michigan's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

Fair-condition bridges (135)

N TWENTIETH ST

M-227(S KALAMAZOO)

M-60 & M-99

J DRIVE S

M-96 (COLUMBIA)

I-69 SB

I-94 BL & M-37

M-99 (SUPERIOR ST)

M-311(11 MILE RD)

MCCAMLY STREET

I-69 NB

4 MILE ROAD

I-194 NB OFF RAMP

I-94 BL (DICKMAN)

P DRIVE SOUTH

I-94 EB

S HANNAH STREET

S HANNAH STREET

M-227 (F DRIVE S)

L DRIVE NORTH

I-94 EB

I-94 WB

I-69 SB COLLECTOR

V DR N

JACKSON RD

J DRIVE N

6 MI ROAD

J DRIVE SOUTH

H DRIVE SOUTH

6 1/2 MILE ROAD

17 1/2 MILE ROAD

I-194

I-194 NB

I-194 SB

I-194

N DRIVE NORTH

I-94 WB

I-94 EB

MAIN ST

I-69 NB COLLECTOR

I-94 BL (MICHIGAN)

I-194

VERONA RD

I-194

11 MI LE ROAD

CUSTER DRIVE

I-69 SB

I-94 BL WB

I-194 & M-66 NB

I-194 & M-66 SB

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