County profile · official public datasets

Marshall County, IA

304 public highway bridges tracked in the FHWA National Bridge Inventory: 32.9% rated Good, 23.7% Fair, 43.4% Poor.

304
Public bridges
32.9%
Good condition
43.4%
Poor condition

The verdict

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

Marshall 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.

98th
of 99 on Poor share
43.4%
Poor-condition share
304
public highway bridges
1970
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.

Marshall County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Marshall County ranks #98 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 43.4%). Marshall County, Iowa contains 304 public highway bridges. Roughly 32.9% are rated “Good,” 23.7% “Fair,” and 43.4% “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

304

Public highway bridges in Marshall County

Good condition

32.9%

100 of 304 rated 7-9

Fair condition

23.7%

72 of 304 rated 5-6

Poor condition

43.4%

132 of 304 rated 4 or below

In-state Poor-share rank

#98 of 99

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

Condition distribution

Share of 304 NBI-tracked bridges by lowest applicable component rating.

Good
32.9% (100)
Fair
23.7% (72)
Poor
43.4% (132)

Marshall County's Poor-condition bridges carry 47,789 vehicle crossings a day

That is 13.6% of the county's reported daily bridge traffic on 43.6% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 362 crossings a day against 1,912 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 303 of 304 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

48.4% of Marshall County's bridges have passed the 50-year mark

147 of the 304 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 32.9% 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 21.9% of the county's Poor-condition bridge traffic

SO CENTER ST over LINN CREEK, built 1951, carries 10,448 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 132-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 47,789 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Marshall County's bridges were built

304 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1980s, when 46 of the county's bridges still in the inventory were built, which is 15.1% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year is 1970, 9 years older than the Iowa average of 1979.

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

How Marshall County compares with Iowa's closest counties by inventory size

The 5 Iowa counties nearest Marshall County in number of bridges, with their condition splits. Its 43.4% Poor share is the 6th-lowest of these 6. Its average build year of 1970 against a peer-group mean of 1980 is 10 years older.

Showing the 5 closest of 98 Iowa counties eligible for comparison.

Bridge inventory size and condition shares for Marshall County and the 5 Iowa counties closest to it in inventory size
County Bridges Poor
Adair County 306 13.4%
Marshall County (this page) 304 43.4%
Chickasaw County 302 27.8%
Cedar County 301 19.6%
Crawford County 301 9%
Story County 296 13.9%

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

Similar inventory size

Nearest county inventories outside IA (304 bridges here).

Similar average build year

Nearest mean year-built outside IA (1970 here).

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

All 304 Good 100 Fair 72 Poor 132

All bridges (304)

US 30 WB

Good

Over: UPRR

0.5 MILE W OF JCT IA 146, Marshall, IA

Built 2003 Load: 46.9 t ADT: 7,050

FM

Good

Over: MINERVA CREEK

085200904, Marshall, IA

Built 1997 Load: 47.1 t ADT: 147

LOCAL

Good

Over: BURNETT CR

084170502, Marshall, IA

Built 2004 Load: 48.0 t ADT: 35

FM

Good

Over: CREEK

084180801, Marshall, IA

Built 2004 Load: 48.0 t ADT: 108

FM

Good

Over: CREEK

084190305, Marshall, IA

Built 2004 Load: 48.0 t ADT: 59

LOCAL

Good

Over: BR MINERVA CREEK

084191501, Marshall, IA

Built 1992 Load: 48.0 t ADT: 21

NB IA 330

Good

Over: US 30

AT JUNCTION WITH US 30, Marshall, IA

Built 2001 Load: 48.0 t ADT: 3,050

FM

Good

Over: BRUSH CREEK

082173401, Marshall, IA

Built 2002 Load: 48.2 t ADT: 442

IA 14

Good

Over: LINN CREEK

IN MARSHALLTOWN, Marshall, IA

Built 1985 Load: 48.3 t ADT: 13,300

HIGHLAND ACRES RD

Good

Over: LINN CREEK

083180912, Marshall, IA

Built 2007 Load: 48.4 t ADT: 1,630

LOCAL

Good

Over: MINERVA CR

084201501, Marshall, IA

Built 2006 Load: 49.8 t ADT: 30

LOCAL

Good

Over: LINN CREEK

084203601, Marshall, IA

Built 1999 Load: 49.8 t ADT: 51

FM

Good

Over: ASHER CREEK

085182801, Marshall, IA

Built 2004 Load: 49.8 t ADT: 29

FM

Good

Over: BURNETT CREEK

084170401, Marshall, IA

Built 1994 Load: 50.0 t ADT: 304

FM

Good

Over: MINERVA CREEK

085200906, Marshall, IA

Built 1997 Load: 50.0 t ADT: 147

LOCAL

Good

Over: CREEK

083170405, Marshall, IA

Built 2003 Load: 51.3 t ADT: 59

LOCAL

Good

Over: DRAINAGE

083180903, Marshall, IA

Built 2006 Load: 51.6 t ADT: 340

JESSUP AVE

Good

Over: LINN CR

083190302, Marshall, IA

Built 2000 Load: 52.7 t ADT: 62

FM

Good

Over: BRUSH CREEK

082170805, Marshall, IA

Built 2002 Load: 52.9 t ADT: 511

FM

Good

Over: MINERVA CREEK

084201102, Marshall, IA

Built 2001 Load: 52.9 t ADT: 501

IA 14

Good

Over: TIMBER CREEK

1.2 MILES S OF JCT. US 30, Marshall, IA

Built 1992 Load: 57.1 t ADT: 4,250

IA 330 NB

Good

Over: NORTH TIMBER CREEK

2.7 MILES S OF JCT US 30, Marshall, IA

Built 2002 Load: 60.5 t ADT: 4,500

FM

Poor

Over: SOUTH TIMBER CREEK

082180902, Marshall, IA

Built 1957 Load: 0.0 t ADT: 39

FM

Poor

Over: SOUTH TIMBER CREEK

083172801, Marshall, IA

Built 1954 Load: 0.0 t ADT: 59

LOCAL

Poor

Over: BURNETT CR

084170402, Marshall, IA

Built 1917 Load: 0.0 t ADT: 5

LOCAL

Poor

Over: BR BURNETT CR

085173101, Marshall, IA

Built 1977 Load: 0.0 t ADT: 5

LOCAL

Poor

Over: DOWD CREEK

085190103, Marshall, IA

Built 1916 Load: 0.0 t ADT: 16

FM

Poor

Over: CREEK

085190602, Marshall, IA

Built 1918 Load: 0.0 t ADT: 25

LOCAL

Poor

Over: BR MINERVA CR

085200502, Marshall, IA

Built 1919 Load: 0.0 t ADT: 30

LOCAL

Poor

Over: MIDDLE TIMBER CREEK

083182604, Marshall, IA

Built 1916 Load: 3.3 t ADT: 51

LOCAL

Poor

Over: BRUSH CREEK

082172705, Marshall, IA

Built 1977 Load: 4.4 t ADT: 47

LOCAL

Poor

Over: CREEK

083171108, Marshall, IA

Built 1916 Load: 4.5 t ADT: 145

LOCAL

Poor

Over: CREEK

083190503, Marshall, IA

Built 1917 Load: 7.4 t ADT: 35

LOCAL

Poor

Over: SNIPE CREEK

082181302, Marshall, IA

Built 1915 Load: 8.9 t ADT: 51

LOCAL

Poor

Over: BRUSH CREEK

082172202, Marshall, IA

Built 1917 Load: 9.9 t ADT: 47

LOCAL

Poor

Over: DOWD CREEK

085190104, Marshall, IA

Built 1916 Load: 10.0 t ADT: 39

LOCAL

Poor

Over: N MINERVA CREEK

085201601, Marshall, IA

Built 1917 Load: 10.0 t ADT: 21

LOCAL

Poor

Over: CREEK

085171402, Marshall, IA

Built 1956 Load: 10.2 t ADT: 16

LOCAL

Poor

Over: LINN CREEK

084202502, Marshall, IA

Built 1919 Load: 10.8 t ADT: 30

LOCAL

Poor

Over: CREEK

083190603, Marshall, IA

Built 1918 Load: 10.9 t ADT: 30

FM

Poor

Over: SOUTH TIMBER CREEK

083173204, Marshall, IA

Built 1942 Load: 11.2 t ADT: 88

LOCAL

Poor

Over: TIMBER CREEK

083182405, Marshall, IA

Built 1942 Load: 11.2 t ADT: 91

FM

Poor

Over: IOWA RIVER

085192707, Marshall, IA

Built 1952 Load: 11.3 t ADT: 49

LOCAL

Poor

Over: DAVISONS CREEK

083172504, Marshall, IA

Built 1951 Load: 11.8 t ADT: 21

LOCAL

Poor

Over: CLEAR CREEK

083203101, Marshall, IA

Built 1941 Load: 12.3 t ADT: 26

LOCAL

Poor

Over: SNIPE CREEK

082193402, Marshall, IA

Built 1920 Load: 12.8 t ADT: 20

LOCAL

Poor

Over: SOUTH TIMBER CREEK

082180104, Marshall, IA

Built 1939 Load: 13.0 t ADT: 16

FM

Poor

Over: STREAM

082202702, Marshall, IA

Built 1935 Load: 13.5 t ADT: 79

FM

Poor

Over: LITTLE ASHER CR

084181602, Marshall, IA

Built 1916 Load: 13.6 t ADT: 118

LOCAL

Poor

Over: SOUTH TIMBER CREEK

082170602, Marshall, IA

Built 1938 Load: 13.7 t ADT: 44

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.