Total bridges
335
Public highway bridges in Shelby County
County profile · official public datasets
Shelby County, IL
335 public highway bridges tracked in the FHWA National Bridge Inventory: 56.4% rated Good, 36.4% Fair, 7.2% Poor.
- 335
- Public bridges
- 56.4%
- Good condition
- 7.2%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Shelby County posts a better-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.
- Top 44%
- lowest Poor share in state
- 7.2%
- Poor-condition share
- 335
- public highway bridges
- 1978
- 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.
Shelby County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Shelby County ranks #45 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 7.2%). Shelby County, Illinois contains 335 public highway bridges. Roughly 56.4% are rated “Good,” 36.4% “Fair,” and 7.2% “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.
Good condition
56.4%
189 of 335 rated 7-9
Fair condition
36.4%
122 of 335 rated 5-6
Poor condition
7.2%
24 of 335 rated 4 or below
In-state Poor-share rank
#45 of 102
Among Illinois counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 335 NBI-tracked bridges by lowest applicable component rating.
Good 56.4% (189)
Fair 36.4% (122)
Poor 7.2% (24)
Shelby County's Poor-condition bridges carry 3,975 vehicle crossings a day
That is 2.7% of the county's reported daily bridge traffic on 7.2% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 166 crossings a day against 292 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 335 of 335 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
32.8% of Shelby County's bridges have passed the 50-year mark
110 of the 335 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 56.4% 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 34% of the county's Poor-condition bridge traffic
TR 62(N. MAIN ST) over LONG GROVE CREEK, built 1953, carries 1,350 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 24-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 3,975 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Shelby County's bridges were built
335 bridges with a recorded construction year, grouped by decade
- pre-1900 1
Built before 1900
1 bridges
- 1900s
1900–1909
27 bridges
- 1910s 5
1910–1919
5 bridges
- 1920s 10
1920–1929
10 bridges
- 1930s 21
1930–1939
21 bridges
- 1940s 5
1940–1949
5 bridges
- 1950s 14
1950–1959
14 bridges
- 1960s 21
1960–1969
21 bridges
- 1970s 14
1970–1979
14 bridges
- 1980s
1980–1989
60 bridges
- 1990s
1990–1999
61 bridges
- 2000s
2000–2009
57 bridges
- 2010s
2010–2019
33 bridges
- 2020s 6
2020–2029
6 bridges
What this shows Construction peaked in the 1990s, when 61 of the county's bridges still in the inventory were built, which is 18.2% of those with a recorded year. That cohort is now 25 to 34 years old in the 2024 inventory. Its average build year (1978) matches the Illinois average (1979).
How Shelby County compares with Illinois's closest counties by inventory size
The 5 Illinois counties nearest Shelby County in number of bridges, with their condition splits. Its 7.2% Poor share is the 3rd-lowest of these 6. Its average build year of 1978 against a peer-group mean of 1981 is in line with the group.
Showing the 5 closest of 101 Illinois counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| DuPage County | 344 | 37.5% | 54.4% | 8.1% | 1985 |
| Stephenson County | 342 | 61.1% | 36.3% | 2.6% | 1977 |
| Kane County | 336 | 48.2% | 45.5% | 6.3% | 1986 |
| Shelby County (this page) | 335 | 56.4% | 36.4% | 7.2% | 1978 |
| Pike County | 330 | 23.9% | 66.1% | 10% | 1979 |
| Henry County | 328 | 49.4% | 39.6% | 11% | 1978 |
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 Shelby 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 Shelby County, both outside Illinois so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside IL (335 bridges here).
- Washington County, KS · 335 bridges
- Iredell County, NC · 335 bridges
- Grand Forks County, ND · 335 bridges
- Jefferson County, AR · 336 bridges
Similar average build year
Nearest mean year-built outside IL (1978 here).
- Orange County, CA · avg 1978 · 1,164 bridges
- Sumner County, KS · avg 1978 · 659 bridges
- Allen County, IN · avg 1978 · 613 bridges
- Buncombe County, NC · avg 1978 · 555 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Fair-condition bridges (122)
FAS 1650(TR 330)
FairOver: SAND CREEK
4.4 MI NW WINDSOR, Shelby, IL
Built 1969 Load: 35.6 t ADT: 75
TR 271 A
FairOver: W BR LITTLE WABASH R
3 MI E OF STRASBURG, Shelby, IL
Built 1991 Load: 36.3 t ADT: 125
FAP 325(IL 16)
FairOver: KASKASKIA RIVER
IN SHELBYVILLE, Shelby, IL
Built 1975 Load: 38.2 t ADT: 6,500
FAP 766(IL 32)
FairOver: BRUSH CREEK
7 MI S OF IL 16, Shelby, IL
Built 1991 Load: 38.2 t ADT: 4,450
FAP 325(ILL 16)
FairOver: STREAM
WCL TOWER HILL, Shelby, IL
Built 1924 Load: 39.2 t ADT: 4,800
TR 266 A
FairOver: JORDAN CREEK
4.2 MI SE SHELBYVLLE, Shelby, IL
Built 1909 Load: 39.2 t ADT: 250
FAS-653
FairOver: Jordan Creek
4 MI SE SHELBYVILLE, Shelby, IL
Built 1990 Load: 40.8 t ADT: 700
CH 18
FairOver: TRIB OF MUD CREEK
W EDGE OF HENTON, Shelby, IL
Built 1961 Load: 41.5 t ADT: 225
US 51 (FAP 322)
FairOver: LONG GROVE CR.
.5 MI N OF MOWEAQUA, Shelby, IL
Built 2002 Load: 42.4 t ADT: 4,800
US 51 (FAP 322)
FairOver: LONG GROVE CR.
.5 MI N OF MOWEAQUA, Shelby, IL
Built 2002 Load: 42.4 t ADT: 4,800
FAS 1656(CH 23)
FairOver: I-57
1 MI N EFF CO LINE, Shelby, IL
Built 1964 Load: 45.0 t ADT: 650
FAP 325 (IL 16)
FairOver: SWAFFORD BRANCH
.75 MI W SHELBYVILLE, Shelby, IL
Built 1991 Load: 45.0 t ADT: 8,200
CH 11(FAS 1629)
FairOver: KASKASKIA RIVER
1.0 MI E COWDEN, Shelby, IL
Built 1968 Load: 45.7 t ADT: 550
US 51 (FAP 322)
FairOver: OPOSSUM CREEK
3 MI S CHRISTIAN LIN, Shelby, IL
Built 1985 Load: 46.0 t ADT: 3,150
FAP 325(ILL 16)
FairOver: ROBINSON CREEK
4.25 MI E TOWER HILL, Shelby, IL
Built 1967 Load: 46.3 t ADT: 5,200
TR 223
FairOver: DRAKE CREEK
5.65 MI NE STRASBURG, Shelby, IL
Built 2016 Load: 48.3 t ADT: 100
TR 223
FairOver: STREAM
1.0 MI NW STRASBURG, Shelby, IL
Built 2013 Load: 48.6 t ADT: 75
CH 33 (FAS 656)
FairOver: LITTLE WABASH RIVER
2 MI W OF NEOGA, Shelby, IL
Built 2013 Load: 48.9 t ADT: 1,250
TR 211A
FairOver: STREAM
1.0 MI SW TOWER HILL, Shelby, IL
Built 2013 Load: 51.5 t ADT: 10
FAP 770 (IL 128)
FairOver: UP RR
1.75 MI S FINDLAY RD, Shelby, IL
Built 2003 Load: 52.2 t ADT: 2,850
FAP 770 (IL 128)
FairOver: ROBINSON CREEK TRIB
.3 MI S FINDLAY RD, Shelby, IL
Built 2009 Load: 54.4 t ADT: 2,850
FAP 774 (IL 128)
FairOver: KASKASKIA RIVER
1 MI SE OF COWDEN, Shelby, IL
Built 1976 Load: 55.4 t ADT: 2,700
Read our methodology - how this data is sourced, computed, and verified.
Related
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.