Structure 21445 · Ada County, ID
Carries Nhs 7553;capitol over Boise River, In Boise;capitol BLVD.
Set by its lowest-rated component: Deck and Superstructure and Substructure at 6 of 9.
How ratings work303 ft end to end, longest span 76 ft: about 4 semi-trucks nose to tail. Lengths and the semi-truck on the deck are drawn to the same scale. 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 deck arch.
| State | Idaho |
| County | Ada |
| Location | In Boise;capitol BLVD |
| Carries | Nhs 7553;capitol |
| Crosses | Boise River |
| Coordinates | 43.60836, -116.20875 |
| Material | Concrete |
| Design | Arch - Deck |
| Total Length | 303.1 ft (92.4 m) |
| Max Span | 76.1 ft (23.2 m) |
| Deck Width | 63.3 ft (19.3 m) |
| Deck Area | 1783.3 sq m |
| Main Spans | 4 |
| Year Built | 1931 (reconstructed 1992) |
| Avg Daily Traffic | 16,500 (2023) |
| Truck Traffic | 2% |
| Lanes On Bridge | 3 |
| Last Inspection | September 2024 |
| Inspection Frequency | Every 24 months |
| Owner | County Highway Agency |
| Historical Significance | Bridge is on the National Register of Historic Places |
| Scour Critical | 3 — Scour critical |
| Structure Number | 000000000021445 |
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.