Road 66B over Colusa Drain
Glenn County, California · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Road 66B over Colusa Drain in Glenn County, California, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the substructure, rated 5 (fair condition) on the 0-9 scale.
- It was built in 1940 and reconstructed in 1974, making it 85 years old at the 2025 inventory.
- It carries about 64 vehicles a day (traffic count year 2011).
- Its listed owner is the county highway agency.
- It is one of 132 of the 240 inventoried bridges in Glenn County rated fair (55.0%); 17 (7.1%) are rated poor.
- Its traffic status in the 2025 inventory is posted for load (NBI item 41).
- Its condition class and component ratings are unchanged from the 2024 inventory.
- Its most recent inspection on record is dated February 2025, on a 12-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 → (39.42852, -122.05017)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 7 | Good condition |
| Superstructure | 7 | 7 | Good condition |
| Substructure | 5 | 5 | Fair condition |
Bridge details
| Structure | Timber stringer or multi-beam girder |
| Length | about 54 ft |
| Location | 2 Mi W of SH 45 |
| NBI structure number | 11C0068 |
| Condition class | Fair |
| Traffic status (item 41) | Posted for load |
| Last inspection (item 90) | February 2025 |
| Inspection interval (item 91) | 12 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 California department of transportation.
Busiest bridges in Glenn County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Interstate 5 over Glenn-colusa Drain Ditch | 1966 | 26,000 | Good |
| Interstate 5 over Logan Creek | 1970 | 25,500 | Good |
| Interstate 5 over North Fork Logan Creek | 1970 | 25,500 | Good |
| Interstate 5 SB over Central Irrigation Canal | 1966 | 13,000 | Good |
| Interstate 5 NB over Central Irrigation Canal | 1966 | 13,000 | Good |
| Interstate 5 SB over Cfnr Spur | 1966 | 13,000 | Good |
All bridges nearby: Glenn County, CA bridge conditions · every bridge in Glenn County · California bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.