County profile · official public datasets

Rock Island County, IL

272 public highway bridges tracked in the FHWA National Bridge Inventory: 46% rated Good, 49.3% Fair, 4.8% Poor.

272
Public bridges: 46%
Good condition: 4.8%
Poor condition

The verdict

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

Rock Island County posts a top-quartile lowest Poor-condition share among rated counties in the state across mid-size county bridge inventory.

Top 14%
lowest Poor share in state: 4.8%
Poor-condition share: 272
public highway bridges: 1983
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.

Rock Island County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Rock Island County ranks #14 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 4.8%). Rock Island County, Illinois contains 272 public highway bridges. Roughly 46% are rated “Good,” 49.3% “Fair,” and 4.8% “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

272

Public highway bridges in Rock Island County

Good condition

46%

125 of 272 rated 7-9

Fair condition

49.3%

134 of 272 rated 5-6

Poor condition

4.8%

13 of 272 rated 4 or below

In-state Poor-share rank

#14 of 102

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

Condition distribution

Share of 272 NBI-tracked bridges by lowest applicable component rating.

Good

46% (125)

Fair

49.3% (134)

Poor

4.8% (13)

Rock Island County's Poor-condition bridges carry 79,325 vehicle crossings a day

That is 4.2% of the county's reported daily bridge traffic on 4.9% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 6,102 crossings a day against 4,523 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 267 of 272 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

31.3% of Rock Island County's bridges have passed the 50-year mark

85 of the 272 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 46% 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 49% of the county's Poor-condition bridge traffic

IL 5 WB (J DEERE R over FAI 74, built 1970, carries 38,900 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 13-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 79,325 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

pre-1900

1
1900s

3
1920s

2
1930s

11
1940s

10
1950s

5
1960s

33
1970s

57
1980s

46
1990s

30
2000s

37
2010s

31
2020s

6

What this shows Construction peaked in the 1970s, when 57 of the county's bridges still in the inventory were built, which is 21% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1983) matches the Illinois average (1979).

How Rock Island County compares with Illinois's closest counties by inventory size

The 5 Illinois counties nearest Rock Island County in number of bridges, with their condition splits. Its 4.8% Poor share is the 2nd-lowest of these 6. Its average build year of 1983 against a peer-group mean of 1980 is in line with the group.

Showing the 5 closest of 101 Illinois counties eligible for comparison.

Bridge inventory size and condition shares for Rock Island County and the 5 Illinois counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Edgar County	278	50.7%	45.3%	4%	1977
Whiteside County	278	19.1%	72.3%	8.6%	1977
Rock Island County (this page)	272	46%	49.3%	4.8%	1983
Grundy County	269	40.5%	32.7%	26.8%	1984
Wayne County	266	54.1%	36.8%	9%	1982
DeKalb County	261	40.6%	46.4%	13%	1981

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 Rock Island 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 Rock Island County, both outside Illinois so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside IL (272 bridges here).

Berrien County, MI · 272 bridges
Bolivar County, MS · 272 bridges
Morton County, ND · 272 bridges
Blaine County, OK · 272 bridges

Similar average build year

Nearest mean year-built outside IL (1983 here).

Dallas County, TX · avg 1983 · 3,230 bridges
Bexar County, TX · avg 1983 · 2,342 bridges
Sedgwick County, KS · avg 1983 · 1,333 bridges
Bernalillo County, NM · avg 1983 · 496 bridges

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

All 272 Good 125 Fair 134 Poor 13

Good-condition bridges (125)

Sort:

Rock Island County Bridge Snapshot

Condition distribution

Rock Island County's Poor-condition bridges carry 79,325 vehicle crossings a day

31.3% of Rock Island County's bridges have passed the 50-year mark

One structure carries 49% of the county's Poor-condition bridge traffic

How Rock Island County compares with Illinois's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

Good-condition bridges (125)

CH 15

TOWNSHIP ROAD 232

TR-62

TR-54

TR-104

FARGO RD

FAS-209 (CH-11)

TR 22-A

COUNTY HIGHWAY 25

13TH ST

TOWNSHIP ROAD 32

24TH ST ROCK ISLAN

24TH ST ROCK ISLAN

MOLINE ROAD

IL 92

US 150

ILL RT 92

43RD AVE

IL 84 & 92

OLD IL 92

IL 5 / JOHN DEERE

IL 84

TOWNSHIP ROAD 96

TOWNSHIP ROAD 6

TOWNSHIP ROAD 151

TOWNSHIP ROAD 52

TOWNSHIP ROAD 44

63 STREET

TR 10-B

TOWNSHIP ROAD 228

TR 71

85 TH AVE W

BARSTOW ROAD / CH

317TH STREET / CH

CH 60 (198TH ST)

CH 64 (320TH ST)

127 TH AVE(CH 55)

175 TH ST (CH 54)

CH 60 (198TH ST W)

CH 60 (198TH ST W)

134TH AVE (TR137)

TR 14 (109TH AVE W

162ND AVE

TR 46 (182ND ST W)

81ST ST.

CH 72

TR 141

154TH AVE

TR 70 (119TH ST. W

TR010

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