Glenn Highway over Knik Riv. Overflow N.B.
Matanuska-Susitna Borough, Alaska · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Glenn Highway over Knik Riv. Overflow N.B. in Matanuska-Susitna Borough, Alaska, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 6 (satisfactory condition) on the 0-9 scale.
- It was built in 1993, making it 32 years old at the 2025 inventory.
- It carries about 13,300 vehicles a day (traffic count year 2020).
- Its listed owner is the state highway agency.
- It is one of 53 of the 121 inventoried bridges in Matanuska-Susitna Borough rated fair (43.8%); 8 (6.6%) 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 July 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 → (61.49472, -149.24417)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 6 | 6 | Satisfactory condition |
| Superstructure | 7 | 7 | Good condition |
| Substructure | 6 | 6 | Satisfactory condition |
Bridge details
| Structure | Prestressed concrete tee beam |
| Length | about 250 ft |
| Location | Mile Point 29.6 |
| NBI structure number | 1888 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | July 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 Alaska department of transportation.
Busiest bridges in Matanuska-Susitna Borough
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Parks Highway over Seward Meridian U.c. | 2005 | 32,100 | Good |
| Glenn Highway over Knik River Access U.c. | 1993 | 26,600 | Good |
| Palmer-wasill Ext over Cottonwood Overhead | 2002 | 14,000 | Fair |
| Glenn Highway over Matanuska Riv Northbound | 1965 | 13,300 | Fair |
| Glenn Highway over Knik Riv. Overflow S.B. | 1993 | 13,300 | Fair |
| Glenn Highway over Matanuska Riv Southbound | 1993 | 13,300 | Fair |
All bridges nearby: Matanuska-Susitna Borough, AK bridge conditions · every bridge in Matanuska-Susitna Borough · Alaska bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.