Tr 18 over Sangamon River
Piatt County, Illinois · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Tr 18 over Sangamon River in Piatt County, Illinois, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 6 (satisfactory condition) on the 0-9 scale.
- It was built in 1991, making it 34 years old at the 2025 inventory.
- It carries about 125 vehicles a day (traffic count year 2020).
- Its listed owner is a town or township highway agency.
- It is one of 95 of the 246 inventoried bridges in Piatt County rated fair (38.6%); 14 (5.7%) are rated poor.
- Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
- It was rated good in the 2024 inventory and is now fair (deck 7 to 6, substructure 8 to 7).
- Its most recent inspection on record is dated February 2025, on a 24-month routine inspection cycle.
- A fair rating means the lowest-rated major component scores 5 or 6 on FHWA's 0-9 scale: some deterioration or minor section loss, but the structure is sound. It is the middle class, not a warning.
View this bridge on a map → (39.97998, -88.68405)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 6 | Satisfactory condition |
| Superstructure | 8 | 8 | Very good condition |
| Substructure | 8 | 7 | Good condition |
Bridge details
| Structure | Steel stringer or multi-beam girder |
| Length | about 511 ft |
| Location | 1 Mi SW Allerton Par |
| NBI structure number | 074322500000000 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | February 2025 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 8: foundations stable, scour above the top of the footing |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Illinois department of transportation.
Busiest bridges in Piatt County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I-74 over Madden Creek Trib | 1971 | 22,800 | Good |
| I-74 over Madden Creek Trib | 1971 | 22,800 | Fair |
| I-74 over Stream | 1970 | 21,500 | Fair |
| I-72 over Stream | 1976 | 11,400 | Fair |
| I-72 over Wolf Run | 1976 | 11,400 | Fair |
| I-74 (EB) over S Branch Salt Creek | 1970 | 10,750 | Fair |
All bridges nearby: Piatt County, IL bridge conditions · every bridge in Piatt County · Illinois bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.