US 310
Carrying US 310 over RR
16M SE BRIDGER, Carbon, Montana
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: US 310
The US 310 bridge in Carbon, Montana carries US 310 over RR. It was built in 2001, making it 25 years old today. The structure is built primarily of steel and spans 3 sections, stretching 74.0 meters (243 feet) end to end. Daily traffic averages 1,513 vehicles, placing it in the moderately-trafficked tier of Montana bridges. It is owned and maintained by State Highway Agency.
The latest FHWA inspection records show a deck rating of 6/9, superstructure at 7/9, substructure at 7/9. The weakest component sits in fair condition. All reported major components score above the Poor range. Its NBI inventory load rating is 37.2 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How US 310 compares
Live comparison across Montana.
Historical Sufficiency Rating
PlainBridge-computedFHWA discontinued this calculated item; it does not determine current condition, funding eligibility, posting, or closure. How the historical reference is calculated.
Condition Ratings
Full 0–9 scale + sufficiency-rating breakdown: how condition ratings work.
Structural Details
- Year Built
- 2001
- Material
- Steel
- Number of Spans
- 3
- Structure Length
- 74.0 m (243 ft)
- Deck Width
- 11.8 m (39 ft)
- Owner
- State Highway Agency
- Avg Daily Traffic
- 1,513 vehicles/day
- Structure Number
- P00004012+00631
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗Condition Analysis
- • The deck (driving surface) rates fair at 6/9, minor deterioration that routine maintenance should address.
- • The superstructure (beams and supports above the deck) rates good at 7/9, with no significant deterioration on file.
- • The substructure (piers and abutments) rates good at 7/9, with no significant deterioration on file.
How to read this record
This page shows what the last federal inspection recorded, not whether US 310 is safe to cross today. Here is how to use it.
- NBI condition ratings reflect the latest record in this annual dataset, not a live status. Current routine inspection intervals are risk-based.
- Learn how the 0–9 condition scale and Good/Fair/Poor categories are defined. How condition ratings work
- Compare US 310 against other structures in Carbon and across Montana. Montana bridges
- Noticed visible damage or a safety concern? Report it to the agency that owns the bridge, or call 911 in an emergency. How to report a bridge
Condition codes come straight from the FHWA National Bridge Inventory and are not a real-time safety judgment. Only the owning agency, a state DOT, county, or other owner, can post, restrict, or close a bridge.
Frequently Asked Questions
What do the condition ratings mean for US 310?
US 310 in Carbon, Montana has a deck rating of 6/9, superstructure rating of 7/9, and substructure rating of 7/9 on the FHWA's 0–9 scale.
How often is US 310 inspected?
US 310's responsible agency sets its routine interval under FHWA's risk-based inspection rules; this page does not expose the scheduled interval. It carries about 1,513 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. US 310 is currently shown as Fair condition from its component ratings; that category is not a live closure or safety decision.
What is the inventory load rating for US 310?
US 310 has an NBI inventory load rating of 37.2 metric tons.
Who is responsible for maintaining US 310?
US 310 is owned and maintained by State Highway Agency.
How old is US 310 and does age affect safety?
US 310 was built in 2001, making it 25 years old.
Disclaimer: Bridge condition data is from the FHWA NBI and reflects the last reported inspection. A Poor condition rating is not a live declaration that a bridge is closed or unsafe for travel. For current closure, posting, or safety information, contact the responsible transportation agency.
Every figure on PlainBridge is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.