County profile · official public datasets

Sangamon County, IL

466 public highway bridges tracked in the FHWA National Bridge Inventory: 56.9% rated Good, 36.9% Fair, 6.2% Poor.

466
Public bridges
56.9%
Good condition
6.2%
Poor condition

The verdict

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

Sangamon County posts a better-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.

Top 28%
lowest Poor share in state
6.2%
Poor-condition share
466
public highway bridges
1981
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.

Sangamon County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Sangamon County ranks #29 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.2%). Sangamon County, Illinois contains 466 public highway bridges. Roughly 56.9% are rated “Good,” 36.9% “Fair,” and 6.2% “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

466

Public highway bridges in Sangamon County

Good condition

56.9%

265 of 466 rated 7-9

Fair condition

36.9%

172 of 466 rated 5-6

Poor condition

6.2%

29 of 466 rated 4 or below

In-state Poor-share rank

#29 of 102

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

Condition distribution

Share of 466 NBI-tracked bridges by lowest applicable component rating.

Good
56.9% (265)
Fair
36.9% (172)
Poor
6.2% (29)

Sangamon County's Poor-condition bridges carry 110,125 vehicle crossings a day

That is 5.7% of the county's reported daily bridge traffic on 6.2% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 3,797 crossings a day against 2,850 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 466 of 466 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

40.3% of Sangamon County's bridges have passed the 50-year mark

188 of the 466 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 56.9% 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 16.2% of the county's Poor-condition bridge traffic

I-55 (SB) over ILLINOIS CENTRAL RR, built 1971, carries 17,850 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 29-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 110,125 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Sangamon County's bridges were built

466 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1970s, when 97 of the county's bridges still in the inventory were built, which is 20.8% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1981) matches the Illinois average (1979).

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

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

The 5 Illinois counties nearest Sangamon County in number of bridges, with their condition splits. Its 6.2% Poor share is the 1st-lowest of these 6. Its average build year of 1981 against a peer-group mean of 1978 is in line with the group.

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

Bridge inventory size and condition shares for Sangamon County and the 5 Illinois counties closest to it in inventory size
County Bridges Poor
LaSalle County 528 12.3%
Madison County 523 8.4%
Vermilion County 494 7.3%
St. Clair County 486 9.1%
Winnebago County 467 7.1%
Sangamon County (this page) 466 6.2%

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

Similar inventory size

Nearest county inventories outside IL (466 bridges here).

Similar average build year

Nearest mean year-built outside IL (1981 here).

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

All 466 Good 265 Fair 172 Poor 29

Good-condition bridges (265)

IL 125

Good

Over: RICHLAND CREEK

.7M E CARTWRIGHT ST., Sangamon, IL

Built 1979 Load: 37.9 t ADT: 5,800

ILL 104

Good

Over: HORSE CREEK

E.PAWNEE CITY LIMITS, Sangamon, IL

Built 1977 Load: 37.9 t ADT: 4,650

FAS 634 CH 01

Good

Over: CANTRALL CREEK

2.5 MI W ANDREW, Sangamon, IL

Built 1984 Load: 37.9 t ADT: 2,500

I-55 (NB)/ I-72 (E

Good

Over: IL 29 / SO GRAND AVE

I-55/IL 29 INT E SPI, Sangamon, IL

Built 1963 Load: 38.6 t ADT: 25,400

IL 123

Good

Over: TRIB FANCY CREEK

2.3M W I55 WILLIAMSV, Sangamon, IL

Built 1991 Load: 39.5 t ADT: 2,300

SUDDUTH RD. FAU 80

Good

Over: I-55

.5M N SHERMAN INTCHG, Sangamon, IL

Built 1962 Load: 39.9 t ADT: 950

FAS 1621

Good

Over: LICK CREEK

2.5 N CHATHAM, Sangamon, IL

Built 1973 Load: 40.2 t ADT: 3,700

VETERANS/IL 4 (NB)

Good

Over: SPRING CREEK

.9M E IL29/WALNUT ST, Sangamon, IL

Built 1997 Load: 40.5 t ADT: 12,400

VETERANS/IL 4 (SB)

Good

Over: SPRING CREEK

.9M E IL29/WALNUT ST, Sangamon, IL

Built 1997 Load: 40.5 t ADT: 12,400

IL 29

Good

Over: CANTRALL CREEK TRIB.

S EDGE CANTRALL, Sangamon, IL

Built 1993 Load: 40.5 t ADT: 2,350

ILL 124

Good

Over: FANCY CREEK

5.8M JCT BUS 55, Sangamon, IL

Built 1990 Load: 41.5 t ADT: 1,000

BL 55 (PEORIA ROAD

Good

Over: SUGAR CREEK

.04M S VETERANS PKWY, Sangamon, IL

Built 1995 Load: 41.5 t ADT: 4,700

CANTRELL RD/ FAS 6

Good

Over: I-72 / US 36

1M W ILLIOPOLIS INT., Sangamon, IL

Built 1974 Load: 41.8 t ADT: 150

IL 29

Good

Over: SANGAMON RIVER TRIB.

.9M N SANGAMON RIVER, Sangamon, IL

Built 1997 Load: 41.8 t ADT: 6,950

KENT FARM RD/ TR 5

Good

Over: I-72 / US 36

3M W ILLIOPOLIS INT., Sangamon, IL

Built 1974 Load: 42.1 t ADT: 10

ILL 54

Good

Over: SANGAMON RIVER

SW EDGE SPAULDING, Sangamon, IL

Built 1997 Load: 42.1 t ADT: 6,000

IL 123

Good

Over: TRIB FANCY CREEK

1.3M W I55 WILLIAMSV, Sangamon, IL

Built 1991 Load: 42.4 t ADT: 2,300

I-55 (SB)

Good

Over: FANCY CREEK

1M N SHERMAN INTCHG, Sangamon, IL

Built 1962 Load: 42.8 t ADT: 14,600

I-55 W FR/W OUTER

Good

Over: FANCY CREEK

1M N SHERMAN INTCHG, Sangamon, IL

Built 1959 Load: 42.8 t ADT: 950

TR 5

Good

Over: Sugar Creek

0.44 mi W TR 70, Sangamon, IL

Built 2019 Load: 42.8 t ADT: 20

TR 171(Oak Crest R

Good

Over: TRIB to Clear Lake

1.3 M SE of Riverton, Sangamon, IL

Built 2020 Load: 42.8 t ADT: 175

IL 125

Good

Over: TRIB PRAIRIE CREEK

2.3 MI W IL 97, Sangamon, IL

Built 2001 Load: 43.1 t ADT: 6,150

TR 134

Good

Over: Sugar Creek Trib

0.62 mi W IL 4, Sangamon, IL

Built 2019 Load: 43.1 t ADT: 75

WASHINGTONFAU-7977

Good

Over: SPRING CREEK

0.02MI WEST KOKEMILL, Sangamon, IL

Built 1984 Load: 43.1 t ADT: 5,100

VETERANS / IL 4 (S

Good

Over: NS RR & GATEWAY W RR

.2M N I-72, Sangamon, IL

Built 1990 Load: 43.4 t ADT: 31,800

TR 281

Good

Over: Lick Creek Trib

0.43 mi W TR 8, Sangamon, IL

Built 2019 Load: 43.4 t ADT: 25

FAS 635

Good

Over: CLEAR CREEK

COUNTY-MECHANICSBURG, Sangamon, IL

Built 1974 Load: 43.7 t ADT: 1,500

CH 28 N PAWNEE RD

Good

Over: BRUSH CREEK

3.0 MI W NEW CITY, Sangamon, IL

Built 1961 Load: 43.7 t ADT: 1,050

TR 384

Good

Over: Wolf Creek

0.29 mi E FAS 633, Sangamon, IL

Built 2019 Load: 43.7 t ADT: 75

TR 138

Good

Over: Panther Creek Trib

0.6 mi S IL 104, Sangamon, IL

Built 2017 Load: 44.4 t ADT: 75

HARRISON AV

Good

Over: SUGAR CREEK

THAYER, Sangamon, IL

Built 1999 Load: 45.0 t ADT: 550

MS 7490A Drawbridg

Good

Over: Jacksonville Branch

0.08 mi S Wabash Av, Sangamon, IL

Built 2021 Load: 45.4 t ADT: 1,600

PULLIAM RD/TR 355

Good

Over: I-55

2.2M N GLENARM INTCH, Sangamon, IL

Built 1971 Load: 45.7 t ADT: 100

SANGAMON AV. (EB)

Good

Over: ILLINOIS CENTRAL RR

.25M W I-55, Sangamon, IL

Built 2003 Load: 45.7 t ADT: 16,700

SANGAMON AV. (WB)

Good

Over: ILLINOIS CENTRAL RR

.25M W I-55, Sangamon, IL

Built 2003 Load: 45.7 t ADT: 16,700

I-55 (NB)

Good

Over: FANCY CREEK

1M N SHERMAN INTCHG, Sangamon, IL

Built 1962 Load: 46.3 t ADT: 14,600

TOLLIVER/BATES RD

Good

Over: I-72 / US 36

5.5M W WABASH INTCHG, Sangamon, IL

Built 1974 Load: 47.0 t ADT: 100

IL 4

Good

Over: POLECAT CREEK

.2 S OF PLUMMER CHTM, Sangamon, IL

Built 2011 Load: 47.0 t ADT: 16,500

FAI 72 (WB)

Good

Over: UPRR/RECREATION DR

1.3M W I-55, Sangamon, IL

Built 1966 Load: 48.3 t ADT: 20,450

FAI 72 (EB)

Good

Over: UPRR/RECREATION DR

1.3M W I-55, Sangamon, IL

Built 1966 Load: 48.6 t ADT: 20,450

JIMTOWN RD (TR 18)

Good

Over: I-72 / US 36

.75M W NEW BERLN INT, Sangamon, IL

Built 1974 Load: 48.6 t ADT: 50

CURRAN RD (OLD IL

Good

Over: PANTHER CREEK

.5M N IL4 N AUBURN, Sangamon, IL

Built 2002 Load: 48.6 t ADT: 1,150

WABASH AVE (FAP 66

Good

Over: JACKSONVILLE BRANCH

.5M E VETERANS/IL 4, Sangamon, IL

Built 1976 Load: 48.6 t ADT: 21,300

FAS 1645 (IL 123)

Good

Over: Ditch

0.14 mi E IL 29, Sangamon, IL

Built 2021 Load: 48.9 t ADT: 525

SNELL RD (OLD IL 4

Good

Over: PANTHER CREEK

.3M W IL4 N AUBURN, Sangamon, IL

Built 2002 Load: 49.2 t ADT: 150

TR 380

Good

Over: SUGAR CREEK

1.0E OF CLEAR LAKE, Sangamon, IL

Built 1963 Load: 49.9 t ADT: 350

TR-52

Good

Over: TRIB S FORK LICK CK

3.5 MI NW LOWDER, Sangamon, IL

Built 2001 Load: 49.9 t ADT: 50

FAS 1645 (IL 123)

Good

Over: Ditch

0.30 mi E IL 29, Sangamon, IL

Built 2021 Load: 50.2 t ADT: 2,450

I-72 / US 36 (EB)

Good

Over: I-55 (SB)

.25M E 6TH ST., Sangamon, IL

Built 1962 Load: 50.5 t ADT: 20,450

I-72 / US 36 (WB)

Good

Over: WABASH AVE (OLD 36)

2.6M W IL4/VETERANS, Sangamon, IL

Built 1974 Load: 50.9 t ADT: 8,550

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.