Structure 31370 · Bonneville County, ID
Carries 55th East Road over Anderson Canal, 4.5 N. Iona.
Set by its lowest-rated component: Deck and Superstructure at 5 of 9.
How ratings work24 ft end to end. Lengths are drawn to scale; at this length a semi-truck would be a speck. Each part is colored by its latest inspection rating. The inventory records lengths but not heights or the layout of the shorter spans, so those are drawn as typical for a rigid-frame bridge.
| State | Idaho |
| County | Bonneville |
| Location | 4.5 N. Iona |
| Carries | 55th East Road |
| Crosses | Anderson Canal |
| Coordinates | 43.59175, -111.92386 |
| Material | Concrete |
| Design | Frame |
| Total Length | 24.0 ft (7.3 m) |
| Max Span | 24.0 ft (7.3 m) |
| Deck Width | 38.4 ft (11.7 m) |
| Deck Area | 85.4 sq m |
| Main Spans | 1 |
| Year Built | 1954 (reconstructed 1971) |
| Avg Daily Traffic | 1,300 (2023) |
| Truck Traffic | 24% |
| Lanes On Bridge | 2 |
| Last Inspection | November 2024 |
| Inspection Frequency | Every 24 months |
| Owner | County Highway Agency |
| Historical Significance | Historical significance is not determined |
| Scour Critical | 8 — Stable, low risk |
| Structure Number | 000000000031370 |
Inspectors rate each major part of a bridge (the deck you drive on, the superstructure of beams that holds it up, and the substructure of piers and abutments beneath) on a 0–9 scale. A bridge's overall condition is its lowest of those ratings, so one deteriorated component makes the whole bridge "poor."
A poor rating is not a closure. It means the bridge is flagged for priority repair or replacement; bridges judged unsafe are closed or posted with weight limits. The waterway (channel) rating is reported, but it does not count toward the overall classification.