Atherton Avenue over Ncrra (old Nwp RR)
Marin County, California · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Atherton Avenue over Ncrra (old Nwp RR) in Marin County, California, is rated in good condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 7 (good condition) on the 0-9 scale.
- It was built in 1974, making it 51 years old at the 2025 inventory.
- It carries about 8,800 vehicles a day (traffic count year 2000).
- Its listed owner is the state highway agency.
- It is one of 91 of the 207 inventoried bridges in Marin County rated good (44.0%); 16 (7.7%) 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 June 2023, on a 24-month routine inspection cycle.
- A good rating means every major component - deck, superstructure, substructure, or culvert - is rated 7 or higher on FHWA's 0-9 scale: no more than minor problems.
View this bridge on a map → (38.11804, -122.56663)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 7 | Good condition |
| Superstructure | 7 | 7 | Good condition |
| Substructure | 7 | 7 | Good condition |
Bridge details
| Structure | Prestressed concrete multiple box beam |
| Length | about 117 ft |
| Location | 04-mrn-101-r22.04-nvto |
| NBI structure number | 27 0104Y |
| Condition class | Good |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | June 2023 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | N: not over a waterway |
Source: FHWA National Bridge Inventory, 2025 data as reported by the California department of transportation.
Busiest bridges in Marin County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US Highway 101 over North San Pedro Road | 1979 | 180,000 | Fair |
| U.S. Highway 101 over Lincoln Ave-n101 on Ramp | 1938 | 180,000 | Fair |
| U.S. Highway 101 over Linden Lane | 1947 | 173,000 | Good |
| U.S. Highway 101 over Ggt Bellam Andersen | 1958 | 172,000 | Good |
| U.S. Highway 101 over Corte Madera CR & Sfd Bl | 1957 | 172,000 | Fair |
| U.S. Highway 101 over Wornum Drive | 1929 | 172,000 | Good |
All bridges nearby: Marin County, CA bridge conditions · every bridge in Marin County · California bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.