Backbone St Pk over Maquoketa River
Delaware County, Iowa · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Backbone St Pk over Maquoketa River in Delaware County, Iowa, is rated in good condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 7 (good condition) on the 0-9 scale.
- It was built in 1989, making it 36 years old at the 2025 inventory.
- It is one of 114 of the 294 inventoried bridges in Delaware County rated good (38.8%); 20 (6.8%) are rated poor.
- 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 → (42.61553, -91.56256)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 7 | Good condition |
| Superstructure | 7 | Good condition |
| Substructure | 7 | Good condition |
Bridge details
| Structure | Continuous concrete slab |
| Length | about 103 ft |
| Location | In Backbone State Park |
| NBI structure number | 000000000699041 |
| Condition class | Good |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Iowa department of transportation.
Busiest bridges in Delaware County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US 20 over Stream | 1963 | 9,700 | Fair |
| US 20 over Stream | 1963 | 9,000 | Good |
| US 20 over Drainage Ditch | 1963 | 9,000 | Fair |
| Ia 13 over Maquoketa River | 1991 | 7,900 | Good |
| Ia 13 over US 20 | 1970 | 6,400 | Fair |
| W Marion St over Maquoketa River | 1980 | 6,294 | Poor |
All bridges nearby: Delaware County, IA bridge conditions · every bridge in Delaware County · Iowa bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.