NB I-29 over Boyer River
Harrison County, Iowa · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- NB I-29 over Boyer River in Harrison County, Iowa, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the superstructure, rated 6 (satisfactory condition) on the 0-9 scale.
- It was built in 1958 and reconstructed in 2009, making it 67 years old at the 2025 inventory.
- It carries about 10,050 vehicles a day (traffic count year 2022).
- Its listed owner is the state highway agency.
- It is one of 120 of the 222 inventoried bridges in Harrison County rated fair (54.1%); 41 (18.5%) 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 August 2023, 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 → (41.5083, -95.90536)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 7 | Good condition |
| Superstructure | 6 | 6 | Satisfactory condition |
| Substructure | 7 | 7 | Good condition |
Bridge details
| Structure | Continuous steel stringer or multi-beam girder |
| Length | about 414 ft |
| Location | 3.0 mi. S of Jct. U.S. 30 |
| NBI structure number | 000000000028060 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | August 2023 |
| 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 Iowa department of transportation.
Busiest bridges in Harrison County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US 30 over Willow Creek | 1972 | 10,300 | Fair |
| US 30 over UPRR | 1998 | 10,300 | Good |
| SB I-29 over Boyer River | 1958 | 10,050 | Fair |
| SB I-29 over over UP RR | 1967 | 7,750 | Fair |
| NB I-29 over Allen Creek | 1967 | 7,750 | Fair |
| SB I-29 over Allen Creek | 1967 | 7,750 | Fair |
All bridges nearby: Harrison County, IA bridge conditions · every bridge in Harrison County · Iowa bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.