Total bridges
225
Public highway bridges in Madison County
County profile · official public datasets
Madison County, IA
225 public highway bridges tracked in the FHWA National Bridge Inventory: 16% rated Good, 46.7% Fair, 37.3% Poor.
- 225
- Public bridges
- 16%
- Good condition
- 37.3%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Madison 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.
- 93rd
- of 99 on Poor share
- 37.3%
- Poor-condition share
- 225
- public highway bridges
- 1968
- 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.
Madison County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Madison County ranks #93 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 37.3%). Madison County, Iowa contains 225 public highway bridges. Roughly 16% are rated “Good,” 46.7% “Fair,” and 37.3% “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.
Good condition
16%
36 of 225 rated 7-9
Fair condition
46.7%
105 of 225 rated 5-6
Poor condition
37.3%
84 of 225 rated 4 or below
In-state Poor-share rank
#93 of 99
Among Iowa counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 225 NBI-tracked bridges by lowest applicable component rating.
Good 16% (36)
Fair 46.7% (105)
Poor 37.3% (84)
Madison County's Poor-condition bridges carry 16,215 vehicle crossings a day
That is 18.1% of the county's reported daily bridge traffic on 37.5% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 193 crossings a day against 373 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 224 of 225 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
54.7% of Madison County's bridges have passed the 50-year mark
123 of the 225 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 16% 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 10.6% of the county's Poor-condition bridge traffic
FM over BR BADGER CREEK, built 1970, carries 1,714 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 84-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 16,215 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Madison County's bridges were built
225 bridges with a recorded construction year, grouped by decade
- pre-1900 3
Built before 1900
3 bridges
- 1900s 3
1900–1909
3 bridges
- 1910s 2
1910–1919
2 bridges
- 1920s 4
1920–1929
4 bridges
- 1930s
1930–1939
21 bridges
- 1940s
1940–1949
21 bridges
- 1950s
1950–1959
33 bridges
- 1960s
1960–1969
24 bridges
- 1970s
1970–1979
32 bridges
- 1980s
1980–1989
32 bridges
- 1990s
1990–1999
27 bridges
- 2000s 8
2000–2009
8 bridges
- 2010s 10
2010–2019
10 bridges
- 2020s 5
2020–2029
5 bridges
What this shows Construction peaked in the 1950s, when 33 of the county's bridges still in the inventory were built, which is 14.7% of those with a recorded year. That cohort is now 65 to 74 years old in the 2024 inventory. Its average build year is 1968, 11 years older than the Iowa average of 1979.
How Madison County compares with Iowa's closest counties by inventory size
The 5 Iowa counties nearest Madison County in number of bridges, with their condition splits. Its 37.3% Poor share is the 5th-lowest of these 6. Its average build year of 1968 against a peer-group mean of 1976 is 8 years older.
Showing the 5 closest of 98 Iowa counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Jones County | 231 | 36.8% | 58.9% | 4.3% | 1981 |
| Franklin County | 228 | 44.7% | 42.1% | 13.2% | 1982 |
| Mahaska County | 225 | 28.4% | 39.1% | 32.4% | 1972 |
| Madison County (this page) | 225 | 16% | 46.7% | 37.3% | 1968 |
| Sac County | 224 | 35.7% | 30.8% | 33.5% | 1973 |
| Taylor County | 220 | 24.5% | 37.7% | 37.7% | 1973 |
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 Madison 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 Madison County, both outside Iowa so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside IA (225 bridges here).
- Dallas County, AL · 225 bridges
- Lincoln County, KS · 225 bridges
- Lenawee County, MI · 225 bridges
- Clay County, MN · 225 bridges
Similar average build year
Nearest mean year-built outside IA (1968 here).
- Montgomery County, PA · avg 1968 · 828 bridges
- San Joaquin County, CA · avg 1968 · 644 bridges
- Providence County, RI · avg 1968 · 476 bridges
- Imperial County, CA · avg 1968 · 444 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
All bridges (225)
FM
PoorOver: DRAINAGE
074293201, Madison, IA
Built 1941 Load: 20.9 t ADT: 20
LOCAL
PoorOver: SMALL STREAM
076273611, Madison, IA
Built 1982 Load: 21.1 t ADT: 71
FM
PoorOver: TOM CREEK
077292702, Madison, IA
Built 1962 Load: 21.2 t ADT: 597
LOCAL
PoorOver: DRAINAGE
075270305, Madison, IA
Built 1952 Load: 21.4 t ADT: 20
LOCAL
PoorOver: DRAINAGE
075282004, Madison, IA
Built 1948 Load: 21.5 t ADT: 26
CO ENTRANCE
PoorOver: DRAINAGE
00000, Madison, IA
Built 1972 Load: 21.5 t ADT: 11
FM
PoorOver: DRAINAGE
075282203, Madison, IA
Built 1975 Load: 21.6 t ADT: 180
FM
PoorOver: DRAINAGE
077271501, Madison, IA
Built 1960 Load: 21.9 t ADT: 40
LOCAL
PoorOver: DRAINAGE
076293602, Madison, IA
Built 1960 Load: 22.0 t ADT: 26
LOCAL
PoorOver: DRAINAGE
077280202, Madison, IA
Built 1955 Load: 22.0 t ADT: 131
FM
PoorOver: FIELD DRAINAGE DITCH
074261601, Madison, IA
Built 1951 Load: 22.2 t ADT: 417
LOCAL RD
PoorOver: SMALL
075291205, Madison, IA
Built 1976 Load: 22.4 t ADT: 60
LOCAL RD
PoorOver: CEDAR CREEK
076282902, Madison, IA
Built 1952 Load: 22.8 t ADT: 29
LOCAL
PoorOver: JIM CREEK
077291402, Madison, IA
Built 1981 Load: 22.8 t ADT: 20
LOCAL
PoorOver: DRAINAGE
075262809, Madison, IA
Built 1952 Load: 23.8 t ADT: 15
LOCAL
PoorOver: DRAINAGE
077271602, Madison, IA
Built 1940 Load: 24.1 t ADT: 90
LOCAL
PoorOver: DRAINAGE
077261103, Madison, IA
Built 1967 Load: 24.4 t ADT: 11
FM
PoorOver: DRAINAGE
074270803, Madison, IA
Built 1930 Load: 26.5 t ADT: 40
FM
PoorOver: OVER-FLOW-NORTH RIVER
077263102, Madison, IA
Built 1970 Load: 26.6 t ADT: 880
FM
PoorOver: FIELD DRAINAGE DITCH
074261701, Madison, IA
Built 1951 Load: 27.1 t ADT: 417
LOCAL
PoorOver: DRAINAGE
076290402, Madison, IA
Built 1952 Load: 28.8 t ADT: 15
LOCAL
PoorOver: WATERWAY
077270303, Madison, IA
Built 1950 Load: 30.2 t ADT: 40
LOCAL
PoorOver: DRAINAGE
074260501, Madison, IA
Built 1981 Load: 30.3 t ADT: 45
FM
PoorOver: JIM CREEK
077290306, Madison, IA
Built 1972 Load: 30.4 t ADT: 597
FM
PoorOver: JONES CREEK
075273102, Madison, IA
Built 1929 Load: 99.9 t ADT: 788
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.