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

Fair-condition bridges (172)

RIDGELY RD

Fair

Over: I-55

.5M S SANG AV/IL 54, Sangamon, IL

Built 1963 Load: 35.6 t ADT: 800

IL 29/J D JONES PK

Fair

Over: SPRING CR OVERFLOW

.34M S VETERANS/IL 4, Sangamon, IL

Built 1975 Load: 35.6 t ADT: 8,300

MADISON ST / IL 97

Fair

Over: WALNUT STREET

1BL N JEFFERSON ST., Sangamon, IL

Built 1993 Load: 35.6 t ADT: 10,700

I-55 (SB)

Fair

Over: ILLINOIS CENTRAL RR

.3M N IL 54/SANG. AV, Sangamon, IL

Built 1963 Load: 36.0 t ADT: 14,600

ILL 97

Fair

Over: RICHLAND CREEK

2.5M S SALISBURY, Sangamon, IL

Built 1936 Load: 36.0 t ADT: 3,850

CLEARLAKE AV/IL29&

Fair

Over: IC(I&M)RR / 19TH ST.

.72M E 9TH ST (BL55), Sangamon, IL

Built 1985 Load: 36.0 t ADT: 18,600

EAST LAKE SHORE DR

Fair

Over: LAKE SPFLD SLOUGH

0.50 mi E I-55, Sangamon, IL

Built 1997 Load: 36.3 t ADT: 2,500

TR 31 FANCY CREEKT

Fair

Over: SANGAMON RIVER

3 MI E SALISBURY, Sangamon, IL

Built 1983 Load: 36.3 t ADT: 200

WAVERLY RD (CH 10)

Fair

Over: I-72 / US 36

NEW BERLIN INTERCHNG, Sangamon, IL

Built 1974 Load: 37.3 t ADT: 3,100

IL 29-J D JONES PK

Fair

Over: SPRING CREEK

.5M S VETERANS(IL 4), Sangamon, IL

Built 1975 Load: 37.3 t ADT: 8,300

6TH ST / BL 55 (NB

Fair

Over: I-55 (SB)

.25M S I-72, Sangamon, IL

Built 1963 Load: 37.6 t ADT: 10,500

FAS 624A (CH 40)

Fair

Over: BRANCH HORSE CREEK

.19 mi W TR 424, Sangamon, IL

Built 1957 Load: 37.6 t ADT: 900

TR 54 (13W)

Fair

Over: LICK CREEK

2.0 W LOAMI, Sangamon, IL

Built 1963 Load: 37.9 t ADT: 75

KOKE MILL ROAD 729

Fair

Over: SPRING CREEK

100 FEET NO.FAU7977, Sangamon, IL

Built 1984 Load: 37.9 t ADT: 1,100

I-55 (SB)/ I-72 (W

Fair

Over: IL 29 / SO GRAND AVE

I-55/IL29 INT E SPI, Sangamon, IL

Built 1963 Load: 38.6 t ADT: 25,400

I-55 (NB)

Fair

Over: ILLINOIS CENTRAL RR

.3M N IL 54/SANG. AV, Sangamon, IL

Built 1963 Load: 38.6 t ADT: 14,600

VETERANS/IL 4 (SB)

Fair

Over: OLD IC RRR.O.W.

.3M N I-72, Sangamon, IL

Built 1973 Load: 38.6 t ADT: 31,800

VETERANS/IL 4 (NB)

Fair

Over: OLD IC RR R.O.W.

.3M N I-72, Sangamon, IL

Built 1973 Load: 38.6 t ADT: 31,800

IL 29 (SB)

Fair

Over: SUGAR CREEK

.7M SE I-55 INTCHG, Sangamon, IL

Built 1963 Load: 38.9 t ADT: 16,700

I-72 / US 36 (WB)

Fair

Over: CLEAR CREEK

2.1M E BUFFALO INTCH, Sangamon, IL

Built 1975 Load: 38.9 t ADT: 7,150

I-72 / US 36 (EB)

Fair

Over: CLEAR CREEK

2.1M E BUFFALO INTCH, Sangamon, IL

Built 1975 Load: 38.9 t ADT: 7,150

BUFFALO-MCHBG/ CH

Fair

Over: I-72 / US 36

1M S BUFFALO, Sangamon, IL

Built 1974 Load: 39.2 t ADT: 1,300

W LAKE SHORE DR

Fair

Over: I-55 / I-72 / US 36

.8M SW STEVENSON INT, Sangamon, IL

Built 1963 Load: 39.5 t ADT: 2,600

VETERANS / IL 4 (S

Fair

Over: LICK CREEK

.3M S WOODSIDE RD, Sangamon, IL

Built 1975 Load: 39.5 t ADT: 22,300

VETERANS / IL 4 (N

Fair

Over: LICK CREEK

.3M S WOODSIDE RD, Sangamon, IL

Built 1975 Load: 39.5 t ADT: 22,300

IL 4 (FAP 662)

Fair

Over: SUGAR CREEK

THAYER 3.3M S IL 104, Sangamon, IL

Built 2002 Load: 39.5 t ADT: 6,000

LINK ROAD

Fair

Over: I-72 / US 36

1.2M E NEW BERLIN IN, Sangamon, IL

Built 1974 Load: 39.9 t ADT: 450

LANESVILLE RD/ CH

Fair

Over: I-72 / US 36

3M E BUFFALO INTCHG, Sangamon, IL

Built 1975 Load: 39.9 t ADT: 100

VETERANS/IL 4 (SB)

Fair

Over: SPRING CREEK

.27M S JEFFRSN/IL125, Sangamon, IL

Built 1984 Load: 39.9 t ADT: 22,100

ILL 97

Fair

Over: RICHLAND CREEK

.5M S SALISBURY, Sangamon, IL

Built 1936 Load: 40.2 t ADT: 4,200

COUNTY HWY 23

Fair

Over: LICK CREEK

1.5 SE OF CURRAN, Sangamon, IL

Built 1963 Load: 40.5 t ADT: 750

I-72 / US 36 (EB)

Fair

Over: LONG POINT SLOUGH

1.5M E ILLIOPLIS INT, Sangamon, IL

Built 1975 Load: 40.8 t ADT: 7,250

I-72 / US 36 (WB)

Fair

Over: LONG POINT SLOUGH

1.5M E ILLIOPLIS INT, Sangamon, IL

Built 1975 Load: 40.8 t ADT: 7,250

VETERANS / IL 4 (S

Fair

Over: I-72 / US 36

VETERANS I-72 INTCHG, Sangamon, IL

Built 1973 Load: 41.1 t ADT: 28,400

VETERANS / IL 4 (N

Fair

Over: I-72 / US 36

VETERANS I-72 INTCHG, Sangamon, IL

Built 1973 Load: 41.1 t ADT: 28,400

OVERPASS RD / TR 4

Fair

Over: I-72 / US 36

1.4M E SANGAMON R., Sangamon, IL

Built 1974 Load: 41.5 t ADT: 3,000

VETERANS / IL 4 (N

Fair

Over: NS RR & GATEWAY W RR

.2M N I-72, Sangamon, IL

Built 1990 Load: 41.5 t ADT: 31,800

IL 104

Fair

Over: BRUSH CREEK

0.90 mi E I-55, Sangamon, IL

Built 1962 Load: 41.8 t ADT: 5,450

ILL 104

Fair

Over: SUGAR CREEK

1.2MI E AUBURN, Sangamon, IL

Built 1993 Load: 41.8 t ADT: 6,000

IL 97

Fair

Over: PRAIRIE CREEK

0.45 mi E IL 125, Sangamon, IL

Built 1941 Load: 42.8 t ADT: 8,500

DAWSON RD / CH 16

Fair

Over: I-72 / US 36

4.5M E SANGAMON R., Sangamon, IL

Built 1975 Load: 42.8 t ADT: 550

MADISON ST/IL 97(E

Fair

Over: JEFFERSON /IL 97(WB)

.7M W WALNUT/IL 29, Sangamon, IL

Built 1994 Load: 42.8 t ADT: 8,700

IL 29 (NB)

Fair

Over: SUGAR CREEK

.7M SE I-55 INTCHG, Sangamon, IL

Built 1928 Load: 43.1 t ADT: 16,700

IL 97 / JEFFERSON

Fair

Over: SPRING CREEK

.08M E IL4/VET. PKWY, Sangamon, IL

Built 1982 Load: 43.1 t ADT: 13,600

CHATHAM ROAD

Fair

Over: I-72/US 36/NS RR

1.5M S WABASH AV, Sangamon, IL

Built 1991 Load: 43.1 t ADT: 8,600

IL 29 (WALNUT ST R

Fair

Over: SANGAMON RIVER

2.6M N IL 4/VETERANS, Sangamon, IL

Built 1997 Load: 43.1 t ADT: 6,950

TR 296 2E

Fair

Over: HENKLE CREEK

1.5 MI SE OF PAWNEE, Sangamon, IL

Built 1900 Load: 43.4 t ADT: 50

FAP 671

Fair

Over: SPRING CREEK

.48MI E OF WALNUT ST, Sangamon, IL

Built 1975 Load: 45.4 t ADT: 5,300

11TH STREET

Fair

Over: I-55 / I-72 / US 36

.45M E 6TH ST., Sangamon, IL

Built 1997 Load: 46.3 t ADT: 7,600

I-72 / US 36

Fair

Over: N FORK CLEAR CR

.75M E DAWSON RD, Sangamon, IL

Built 1975 Load: 46.3 t ADT: 14,500

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.