Tr 506 over Little Blue Creek
Pike County, Illinois · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Tr 506 over Little Blue Creek in Pike County, Illinois, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the superstructure, rated 5 (fair condition) on the 0-9 scale.
- It was built in 1961, making it 64 years old at the 2025 inventory.
- It carries about 50 vehicles a day (traffic count year 2023).
- Its listed owner is a town or township highway agency.
- It is one of 220 of the 332 inventoried bridges in Pike County rated fair (66.3%); 34 (10.2%) are rated poor.
- Its traffic status in the 2025 inventory is posted for load (NBI item 41).
- Its condition class and component ratings are unchanged from the 2024 inventory.
- Its most recent inspection on record is dated April 2023, on a 24-month routine inspection cycle.
- It has fracture-critical members (NBI item 92A): steel tension members without a redundant load path, which get their own scheduled inspections.
- 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 → (39.60198, -90.62335)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 8 | 8 | Very good condition |
| Superstructure | 5 | 5 | Fair condition |
| Substructure | 7 | 7 | Good condition |
Bridge details
| Structure | Steel through truss |
| Length | about 104 ft |
| Location | 2.75MI SE Detroit |
| NBI structure number | 075318100000000 |
| Condition class | Fair |
| Traffic status (item 41) | Posted for load |
| Last inspection (item 90) | April 2023 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 8: foundations stable, scour above the top of the footing |
| Fracture critical (item 92A) | Yes |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Illinois department of transportation.
Busiest bridges in Pike County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I-72 / US 36 over Miss R/bnrr/nsrr/st | 1999 | 16,500 | Poor |
| I-72 over Trib Blue Creek | 1988 | 9,900 | Good |
| I-72 over Drainage Ditch | 1988 | 9,410 | Good |
| I-72 over Drainage Ditch | 1986 | 9,400 | Fair |
| I-72 over Drainage Ditch | 1986 | 9,400 | Fair |
| I-72 / US 36 over Drainage Ditch | 1986 | 9,400 | Fair |
All bridges nearby: Pike County, IL bridge conditions · every bridge in Pike County · Illinois bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.