15TH ST N-US 87
Carrying 15TH ST N-US 87 over MISSOURI R-RIVERS TRAIL
GREAT FALLS-15TH ST N, Cascade, Montana
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: 15TH ST N-US 87
The 15TH ST N-US 87 bridge in Cascade, Montana carries 15TH ST N-US 87 over MISSOURI R-RIVERS TRAIL. It was built in 1962, making it 64 years old today. It was last reconstructed in 1982, extending its service life. The structure is built primarily of steel continuous and spans 6 sections, stretching 343.1 meters (1126 feet) end to end. Daily traffic averages 13,743 vehicles, placing it in the heavily-trafficked tier of Montana bridges. It is owned and maintained by State Highway Agency.
The latest FHWA inspection records show a deck rating of 5/9, superstructure at 6/9, substructure at 5/9. The weakest component sits in fair condition. No reported major component scores in the Poor range under the current federal condition thresholds. Its NBI inventory load rating is 17.2 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How 15TH ST N-US 87 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 How the historical reference is calculated.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
- 1962
- Last Reconstructed
- 1982
- Material
- Steel Continuous
- Number of Spans
- 6
- Structure Length
- 343.1 m (1126 ft)
- Deck Width
- 20.5 m (67 ft)
- Owner
- State Highway Agency
- Avg Daily Traffic
- 13,743 vehicles/day
- Structure Number
- P00010003+05341
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗Condition Analysis
- • The deck (driving surface) is in fair condition (5/9), with minor deterioration that may require routine maintenance.
- • The superstructure (beams and supports above the deck) is in fair condition (6/9), with minor deterioration that may require routine maintenance.
- • At 5/9, the substructure (piers and abutments) shows fair condition, with minor wear flagged for upkeep.
How to read this record
This page shows what the last federal inspection recorded, not whether 15TH ST N-US 87 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 15TH ST N-US 87 against other structures in Cascade 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 15TH ST N-US 87?
15TH ST N-US 87 in Cascade, Montana has a deck rating of 5/9, superstructure rating of 6/9, and substructure rating of 5/9 on the FHWA's 0–9 scale.
How often is 15TH ST N-US 87 inspected?
15TH ST N-US 87'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 13,743 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. 15TH ST N-US 87 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 15TH ST N-US 87?
15TH ST N-US 87 has an NBI inventory load rating of 17.2 metric tons.
Who is responsible for maintaining 15TH ST N-US 87?
15TH ST N-US 87 is owned and maintained by State Highway Agency.
How old is 15TH ST N-US 87 and does age affect safety?
15TH ST N-US 87 was built in 1962, making it 64 years old and last reconstructed in 1982.
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.