SB I-29 over Robinson Ditch
Monona County, Iowa · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- SB I-29 over Robinson Ditch in Monona 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 2009, making it 16 years old at the 2025 inventory.
- It carries about 7,800 vehicles a day (traffic count year 2022).
- Its listed owner is the state highway agency.
- It is one of 60 of the 160 inventoried bridges in Monona County rated good (37.5%); 41 (25.6%) 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 April 2024, on a 24-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 → (42.17126, -96.23002)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 7 | Good condition |
| Superstructure | 7 | 7 | Good condition |
| Substructure | 8 | 8 | Very good condition |
Bridge details
| Structure | Continuous concrete slab |
| Length | about 103 ft |
| Location | 4.1 mi S of jct IA 141 |
| NBI structure number | 000000000037361 |
| Condition class | Good |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | April 2024 |
| Inspection interval (item 91) | 24 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 Iowa department of transportation.
Busiest bridges in Monona County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| NB I-29 over Robinson Ditch | 2011 | 7,800 | Good |
| NB I-29 over Cleghorn Creek | 2012 | 7,250 | Good |
| SB I-29 over Cleghorn Creek | 2011 | 7,250 | Good |
| Ia 175 over Mccandlesscleghorn Ditch | 2023 | 5,300 | Good |
| Ia 175 over I-29 | 1959 | 4,090 | Poor |
| Ia 141 & 175 over Maple River | 1967 | 3,720 | Poor |
All bridges nearby: Monona County, IA bridge conditions · every bridge in Monona County · Iowa bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.