Twin Lakes Road over BLDR and Whiterock Ditch
Boulder County, Colorado · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Twin Lakes Road over BLDR and Whiterock Ditch in Boulder County, Colorado, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the culvert, rated 5 (fair condition) on the 0-9 scale.
- It was built in 1975, making it 50 years old at the 2025 inventory.
- It carries about 1,018 vehicles a day (traffic count year 2023).
- Its listed owner is the county highway agency.
- It is one of 211 of the 321 inventoried bridges in Boulder County rated fair (65.7%); 7 (2.2%) are rated poor.
- Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
- Its class is unchanged from 2024 (fair), but component ratings moved: culvert 6 to 5.
- Its most recent inspection on record is dated January 2025, 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 → (40.05731, -105.20251)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Culvert | 6 | 5 | Fair condition |
Bridge details
| Structure | Concrete culvert |
| Length | about 20 ft |
| Location | 0.2 Mi E of 63rd Street |
| NBI structure number | BC-O-OSO-8A |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | January 2025 |
| 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 Colorado department of transportation.
Busiest bridges in Boulder County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US 36 Ml over South Boulder Creek | 1951 | 77,000 | Good |
| US 36 Ml over Davidson Ditch | 2015 | 77,000 | Good |
| US 36 Ml over Coal Creek | 2015 | 66,000 | Good |
| US 36 Ml over Canyon Creek | 1951 | 45,000 | Fair |
| Table Mesa Drive over US 36 Ml | 1951 | 44,000 | Fair |
| SH 157 Ramp over US 36 Ml | 1971 | 44,000 | Fair |
All bridges nearby: Boulder County, CO bridge conditions · every bridge in Boulder County · Colorado bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.