IRR CO RD 87 over Mamath Slough
GoodModoc County, California · 0.5 MI NE CR 91 · Structure no. 03C0071
- Built
- 1955
- 70 years old
- Condition
- Good
- inspected April 2023
- Type
- Slab
- Concrete
- Length
- 23 ft
- 1 main span
- Daily traffic
- 255
- 2006 count
- Owner
- County
- County Highway Agency
About this bridge
IRR CO RD 87 over Mamath Slough is a concrete slab carrying IRR CO RD 87 over Mamath Slough in Modoc County, California. It was built in 1955, so it is 70 years old, older than the California average of 54.8 years.
The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.
It carries about 255 vehicles a day, roughly 10% of them trucks, projected to reach 535 by 2045. The structure is 23 ft (7 m) long and 29 ft wide. If it were closed, the detour would be 14.9 mi (24 km).
Location
Open in Google MapsCondition and inspection
All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 7 Good | Some minor problems. |
| Superstructure | 7 Good | Some minor problems. |
| Substructure | 7 Good | Some minor problems. |
| Channel and channel protection | 8 Very Good | No problems noted. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was IRR CO RD 87 over Mamath Slough built?
It was built in 1955, making it 70 years old in 2025.
What condition is IRR CO RD 87 over Mamath Slough in?
The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in April 2023.
How much traffic does IRR CO RD 87 over Mamath Slough carry?
About 255 vehicles per day (2006 count), of which roughly 10% are trucks.
How long is IRR CO RD 87 over Mamath Slough?
The structure is 23 ft (7 m) long with a longest span of 20 ft (6.1 m) and a deck 29 ft wide.
Who owns IRR CO RD 87 over Mamath Slough?
It is owned by the County Highway Agency.