County profile · official public datasets

Johnson County, IL

118 public highway bridges tracked in the FHWA National Bridge Inventory: 58.5% rated Good, 39% Fair, 2.5% Poor.

118
Public bridges
58.5%
Good condition
2.5%
Poor condition

The verdict

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

Johnson County posts a top-5% lowest Poor-condition share among rated counties in the state across mid-size county bridge inventory.

Top 3%
lowest Poor share in state
2.5%
Poor-condition share
118
public highway bridges
1979
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.

Johnson County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Johnson County ranks #3 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 2.5%). Johnson County, Illinois contains 118 public highway bridges. Roughly 58.5% are rated “Good,” 39% “Fair,” and 2.5% “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

118

Public highway bridges in Johnson County

Good condition

58.5%

69 of 118 rated 7-9

Fair condition

39%

46 of 118 rated 5-6

Poor condition

2.5%

3 of 118 rated 4 or below

In-state Poor-share rank

#3 of 102

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

Condition distribution

Share of 118 NBI-tracked bridges by lowest applicable component rating.

Good
58.5% (69)
Fair
39% (46)
Poor
2.5% (3)

Johnson County's Poor-condition bridges carry 454 vehicle crossings a day

That is 0.2% of the county's reported daily bridge traffic on 2.6% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 151 crossings a day against 1,186 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 117 of 118 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

42.4% of Johnson County's bridges have passed the 50-year mark

50 of the 118 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 58.5% 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 49.6% of the county's Poor-condition bridge traffic

TR 111 over DUTCHMAN CR. TRIB., built 1978, carries 225 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 3-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 454 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Johnson County's bridges were built

118 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1970s, when 37 of the county's bridges still in the inventory were built, which is 31.4% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1979) matches the Illinois average (1979).

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

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

The 5 Illinois counties nearest Johnson County in number of bridges, with their condition splits. Its 2.5% Poor share is the 1st-lowest of these 6. Its average build year of 1979 against a peer-group mean of 1984 is 5 years older.

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

Bridge inventory size and condition shares for Johnson County and the 5 Illinois counties closest to it in inventory size
County Bridges Poor
Kendall County 132 12.1%
Johnson County (this page) 118 2.5%
Schuyler County 114 10.5%
Jersey County 113 4.4%
Boone County 109 6.4%
Pulaski County 108 8.3%

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

Similar inventory size

Nearest county inventories outside IL (118 bridges here).

Similar average build year

Nearest mean year-built outside IL (1979 here).

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

All 118 Good 69 Fair 46 Poor 3

All bridges (118)

SIDE STREET

Fair

Over: UNION PACIFIC RR

GOREVILLE E.ILL 37, Johnson, IL

Built 1900 Load: 13.0 t ADT: 25

US 45

Fair

Over: STREAM

1 MI.S.NEW BURNSIDE, Johnson, IL

Built 1922 Load: 17.2 t ADT: 1,750

ILL 146

Fair

Over: TRIB OF BUCK RUN

1.9M E.UNION CO., Johnson, IL

Built 1930 Load: 17.8 t ADT: 2,250

FAS 928

Fair

Over: CACHE RIVER

NW1/4 SEC 6 T14S R3E, Johnson, IL

Built 1948 Load: 21.1 t ADT: 550

FAS 924

Fair

Over: LICK CREEK

NW1/4 SEC 9 T12S R2E, Johnson, IL

Built 1962 Load: 26.2 t ADT: 175

ILL 37

Fair

Over: INTERSTATE 24

1.5 MI N GOREVILLE, Johnson, IL

Built 1972 Load: 28.8 t ADT: 4,600

TR 140 CENTRAL HIL

Fair

Over: INTERSTATE 24

9 MI S E OF VIENNA, Johnson, IL

Built 1970 Load: 28.8 t ADT: 75

FAS 932 - ILL 147

Fair

Over: MAX CR

2.4 MI W OF SIMPSON, Johnson, IL

Built 1987 Load: 29.2 t ADT: 650

FAS 927 TUNNEL HIL

Fair

Over: INTERSTATE 24

GOREVILLE INTERCH., Johnson, IL

Built 1971 Load: 29.5 t ADT: 1,700

US 45

Fair

Over: STREAM

N OF BLOOMFIELD, Johnson, IL

Built 1953 Load: 30.5 t ADT: 2,150

I 24 EB

Fair

Over: TR 102 OLD BLOOMFLD

1.2 MI N ILL 146, Johnson, IL

Built 1971 Load: 31.1 t ADT: 10,650

I 24 WB

Fair

Over: TR 102 OLD BLOOMFLD

1.2 MI N ILL 146, Johnson, IL

Built 1971 Load: 31.1 t ADT: 10,650

I 24 EB

Fair

Over: ILL 146

1 MI E OF VIENNA, Johnson, IL

Built 1971 Load: 32.4 t ADT: 10,600

I 24 WB

Fair

Over: ILL 146

1 MI E OF VIENNA, Johnson, IL

Built 1971 Load: 32.4 t ADT: 10,600

FAS 924

Fair

Over: LICK CREEK OVERFLOW

NE1/4 SEC 8 T12S R2E, Johnson, IL

Built 1962 Load: 32.4 t ADT: 175

FAS 924

Fair

Over: LICK CR

E 1/2 SEC 6 T12S R2E, Johnson, IL

Built 1974 Load: 32.4 t ADT: 375

TR 164

Fair

Over: CEDAR CREEK

NW1/4 SEC10 T12S R4E, Johnson, IL

Built 1983 Load: 32.4 t ADT: 100

FAS 927

Fair

Over: TRIB TO CEDAR CREEK

0.5 MI NW OF SIMPSON, Johnson, IL

Built 1990 Load: 32.4 t ADT: 450

TR 111

Fair

Over: TRIB TO LITTLE CACHE

1 MI N VIENNA, Johnson, IL

Built 1993 Load: 32.4 t ADT: 225

TR 67

Fair

Over: DUTCHMAN CREEK

NW1/4 SEC36 T11S R2E, Johnson, IL

Built 2003 Load: 32.4 t ADT: 75

TR 35

Fair

Over: CLIFTY CREEK

2 MI E NEW BURNSIDE, Johnson, IL

Built 1997 Load: 32.4 t ADT: 10

ILL 37

Fair

Over: BEAR BRANCH

0.45M N OF CYPRESS, Johnson, IL

Built 1933 Load: 33.0 t ADT: 1,350

TR 96 DUTCHMAN LAK

Fair

Over: INTERSTATE 24

6.5 MI S.E. OF ILL37, Johnson, IL

Built 1972 Load: 33.4 t ADT: 175

I 24 WB

Fair

Over: TR 173 BETHLEHEM CH

7 MI S E OF VIENNA, Johnson, IL

Built 1971 Load: 34.3 t ADT: 10,600

US 45

Fair

Over: STREAM

S OF WILLIAMSON CO, Johnson, IL

Built 1956 Load: 34.7 t ADT: 1,450

I 24 EB

Fair

Over: TR 173 BETHLEHEM CH

7 MI S E OF VIENNA, Johnson, IL

Built 1971 Load: 34.7 t ADT: 10,600

TR 82 DEER RIDGE R

Fair

Over: INTERSTATE 24

2.5 MI E OF ILL 37, Johnson, IL

Built 1972 Load: 35.3 t ADT: 275

ILL 37

Fair

Over: ABANDONED RR

0.2 MI S CYPRESS, Johnson, IL

Built 1934 Load: 36.0 t ADT: 1,200

ILL 37

Fair

Over: CACHE RIVER

.5 MI S. OF W VIENNA, Johnson, IL

Built 1931 Load: 36.9 t ADT: 1,350

I 24 WB

Fair

Over: US 45

1.5 MI N OF VIENNA, Johnson, IL

Built 1971 Load: 37.9 t ADT: 11,050

I 24 EB

Fair

Over: US 45

1.5 MI N OF VIENNA, Johnson, IL

Built 1971 Load: 37.9 t ADT: 10,650

US 45

Fair

Over: CAVE CREEK

1.7 MI N MASSAC CO, Johnson, IL

Built 1920 Load: 38.6 t ADT: 2,000

ILL 146

Fair

Over: CACHE RIVER

1 MI W OF W VIENNA, Johnson, IL

Built 1930 Load: 38.6 t ADT: 2,250

I 24 EB

Fair

Over: TR 42 & L SALINE R

1.7 MI SE I-57, Johnson, IL

Built 1972 Load: 39.5 t ADT: 11,150

I 24 WB

Fair

Over: TR 42 & L SALINE R

1.7 MI SE I-57, Johnson, IL

Built 1972 Load: 39.5 t ADT: 11,150

ILL 147

Fair

Over: BAY CREEK

0.2 MI W POPE CO L., Johnson, IL

Built 1936 Load: 40.2 t ADT: 400

US 45

Fair

Over: MCCORKLE CREEK

0.3 MI S OF ILL 146, Johnson, IL

Built 1924 Load: 43.7 t ADT: 2,000

FAS 1931

Fair

Over: INTERSTATE 57

2.7 MI W GOREVILLE, Johnson, IL

Built 1959 Load: 45.0 t ADT: 1,050

ILL 146

Fair

Over: BELL POND CREEK

0.5 MI E GRANTSBURG, Johnson, IL

Built 1931 Load: 46.0 t ADT: 900

I 24 WB

Fair

Over: TUNNEL HILL STATE TR

1 MI N OF ILL 146, Johnson, IL

Built 1971 Load: 51.8 t ADT: 10,650

I 24 EB

Fair

Over: TUNNEL HILL STATE TR

1 MI N OF ILL 146, Johnson, IL

Built 1971 Load: 51.8 t ADT: 10,650

IL 146-FAP 885

Fair

Over: CN/IC RAILROAD

0.3 MI W POPE CO, Johnson, IL

Built 2002 Load: 52.5 t ADT: 900

I 24 EB

Fair

Over: TR 77 BOWMAN BOTTOMS

3.1 MI NW US 45, Johnson, IL

Built 1971 Load: 59.6 t ADT: 11,050

I 24 WB

Fair

Over: TR 77 BOWMAN BOTTOMS

3.1 MI NW US 45, Johnson, IL

Built 1971 Load: 59.6 t ADT: 11,050

I 24

Fair

Over: DRY FORK CREEK

1.88M E OF ILL 37, Johnson, IL

Built 1976 Load: 89.1 t ADT: 22,300

US 45

Fair

Over: STREAM

2.3 MI S VIENNA, Johnson, IL

Built 1972 Load: 97.2 t ADT: 2,000

TR 153

Good

Over: CACHE R.

SW1/4 SEC10 T13S R2E, Johnson, IL

Built 1977 Load: 24.3 t ADT: 25

TR 101

Good

Over: CACHE RIVER

NW1/4 SEC20 T12S R2E, Johnson, IL

Built 1979 Load: 24.3 t ADT: 25

TWP RD 111

Good

Over: DRAINAGE DITCH

SW1/4 SEC14 T12S R2E, Johnson, IL

Built 1977 Load: 24.3 t ADT: 225

FAS 929-CH 5

Good

Over: CLIFTY CR

SW1/4 SEC30 T13S R4E, Johnson, IL

Built 1974 Load: 32.1 t ADT: 500

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.