N Siedschlag Road over Rock Run
Stephenson County, Illinois · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- N Siedschlag Road over Rock Run in Stephenson County, Illinois, is rated in good condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 8 (very good condition) on the 0-9 scale.
- It was built in 1986, making it 39 years old at the 2025 inventory.
- It carries about 50 vehicles a day (traffic count year 2020).
- Its listed owner is a town or township highway agency.
- It is one of 203 of the 340 inventoried bridges in Stephenson County rated good (59.7%); 11 (3.2%) are rated poor.
- Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
- Its condition class and component ratings are unchanged from the 2024 inventory.
- Its most recent inspection on record is dated October 2024, on a 48-month routine inspection cycle.
- A good rating means every major component - deck, superstructure, substructure, or culvert - is rated 7 or higher on FHWA's 0-9 scale: no more than minor problems.
View this bridge on a map → (42.46432, -89.46831)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 8 | 8 | Very good condition |
| Superstructure | 8 | 8 | Very good condition |
| Substructure | 8 | 8 | Very good condition |
Bridge details
| Structure | Prestressed concrete multiple box beam |
| Length | about 55 ft |
| Location | 4 Mi N of Rock City |
| NBI structure number | 089325700000000 |
| Condition class | Good |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | October 2024 |
| Inspection interval (item 91) | 48 months |
| Scour (item 113) | 5: foundations stable, scour within the limits of the footing or piles |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Illinois department of transportation.
Busiest bridges in Stephenson County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US 20 EB over Sumner Creek | 1959 | 12,700 | Fair |
| US 20 WB over Wickham Creek | 1983 | 12,700 | Fair |
| US 20WB over Sumner Creek | 1994 | 12,700 | Good |
| US 20 EB over Wickham Creek | 1999 | 12,700 | Fair |
| US 20 & Private Rd over Silver Creek Trib | 1959 | 12,700 | Fair |
| Il 26 over Yellow Creek | 1988 | 12,600 | Fair |
All bridges nearby: Stephenson County, IL bridge conditions · every bridge in Stephenson County · Illinois bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.