SH 21 over Boise River
Good Condition30 years old6,800 vehicles/day
Location
| State | Idaho |
| County | Ada |
| Location | Near Diversion Dam |
| Carries | SH 21 |
| Crosses | Boise River |
| Coordinates | 43.54359, -116.10214 |
Condition Ratings
| Overall Condition | Good |
| Deck | 7 (Good) |
| Superstructure | 7 (Good) |
| Substructure | 7 (Good) |
| Channel/Waterway | 9 (Excellent) |
| Scour Critical | 8 — Stable, low risk |
Physical Characteristics
| Material | Steel |
| Design | Stringer/Multi-beam |
| Total Length | 1495.1 ft (455.7 m) |
| Max Span | 185.0 ft (56.4 m) |
| Deck Width | 41.7 ft (12.7 m) |
| Deck Area | 5787.4 sq m |
| Main Spans | 9 |
| Year Built | 1996 |
Traffic
| Avg Daily Traffic | 6,800 (2023) |
| Truck Traffic | 11% |
| Lanes On Bridge | 2 |
Inspection & Ownership
| Last Inspection | 122 |
| Inspection Frequency | Every 48 months |
| Owner | State Highway Agency |
| Historical Significance | Historical significance is not determined |
| Structure Number | 000000000015769 |