OLD HWY 312
Carrying OLD HWY 312 over YELLOWSTONE RIVER 170
HUNTLEY, Yellowstone, Montana
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: OLD HWY 312
The OLD HWY 312 bridge in Yellowstone, Montana carries OLD HWY 312 over YELLOWSTONE RIVER 170. It was built in 1949, making it 77 years old today. The structure is built primarily of steel continuous and spans 6 sections, stretching 311.5 meters (1022 feet) end to end. Daily traffic averages 3,981 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 4/9, superstructure at 6/9, substructure at 5/9. The weakest component sits in poor condition. At least one major component here scores 4 or below, which produces a Poor condition classification under FHWA's current reporting rules. Its NBI inventory load rating is 23.6 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How OLD HWY 312 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 How the historical reference is calculated.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
- 1949
- Material
- Steel Continuous
- Number of Spans
- 6
- Structure Length
- 311.5 m (1022 ft)
- Deck Width
- 10.3 m (34 ft)
- Owner
- State Highway Agency
- Avg Daily Traffic
- 3,981 vehicles/day
- Structure Number
- L56788012+07001
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗Condition Analysis
- • The deck (driving surface) rates poor at 4/9, advanced deterioration that should be prioritized for repair.
- • At 6/9, the superstructure (beams and supports above the deck) shows fair condition, with minor wear flagged for upkeep.
- • At 5/9, the substructure (piers and abutments) shows fair condition, with minor wear flagged for upkeep.
How to read this record
OLD HWY 312 is in the federal Poor condition category. That is a component-based result, not a closure order.
- NBI condition ratings reflect the latest record in this annual dataset, not a live status. Current routine inspection intervals are risk-based.
- Understand what Poor condition does and does not mean before drawing conclusions. Poor condition explained
- Compare OLD HWY 312 against other structures in Yellowstone 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 OLD HWY 312?
OLD HWY 312 in Yellowstone, Montana has a deck rating of 4/9, superstructure rating of 6/9, and substructure rating of 5/9 on the FHWA's 0–9 scale.
How often is OLD HWY 312 inspected?
OLD HWY 312'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 3,981 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. OLD HWY 312 is currently shown as Poor condition from its component ratings; that category is not a live closure or safety decision.
What is the inventory load rating for OLD HWY 312?
OLD HWY 312 has an NBI inventory load rating of 23.6 metric tons.
Who is responsible for maintaining OLD HWY 312?
OLD HWY 312 is owned and maintained by State Highway Agency.
How old is OLD HWY 312 and does age affect safety?
OLD HWY 312 was built in 1949, making it 77 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.