Sth 21 over Spring Brook
Winnebago County, Wisconsin · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Sth 21 over Spring Brook in Winnebago County, Wisconsin, 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 1988, making it 37 years old at the 2025 inventory.
- It carries about 10,300 vehicles a day (traffic count year 2024).
- Its listed owner is the state highway agency.
- It is one of 94 of the 265 inventoried bridges in Winnebago County rated fair (35.5%); 8 (3.0%) 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 November 2024, on a 48-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 → (44.03374, -88.68759)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 6 | 6 | Satisfactory condition |
| Superstructure | 6 | 6 | Satisfactory condition |
| Substructure | 8 | 8 | Very good condition |
Bridge details
| Structure | Continuous concrete slab |
| Length | about 65 ft |
| Location | 3.0M E Jct Sth 116 to W |
| NBI structure number | B70010500000000 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | November 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 Wisconsin department of transportation.
Busiest bridges in Winnebago County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Ih 41 over S Br Mud Creek | 1935 | 88,300 | Fair |
| Ih 41 over Neenah Slough | 1975 | 65,700 | Fair |
| Ih 41 over Trib Lake Butte Des Mort | 2011 | 59,900 | Good |
| Ush 10 Wb/sth 441 over Cth Ap (midway Rd) | 2018 | 52,300 | Good |
| Ih 41 SB over Menasha Creek | 1992 | 52,000 | Fair |
| Ih 41 NB over Menasha Creek | 1992 | 52,000 | Fair |
All bridges nearby: Winnebago County, WI bridge conditions · every bridge in Winnebago County · Wisconsin bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.