15TH ST N-US 87
Carrying 15TH ST N-US 87 over MISSOURI R-RIVERS TRAIL
GREAT FALLS-15TH ST N, Cascade, Montana
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
15TH ST N-US 87 in Cascade, Montana sits above 9% of rated Montana bridges on inventory load rating (17 t), while its 1962 build year is earlier than 51% of Cascade's recorded-year cohort (185 bridges).
15TH ST N-US 87 in Cascade, Montana is rated Fair in the FHWA's 2024 National Bridge Inventory. Built in 1962, it carries 3 rated components on the inspecting agency's 0-9 scale, and its weakest reported component scores 5. The lowest applicable rating sets the federal condition category, so this Fair result describes the weakest reported component rather than the structure as a whole. No NBI category is a closure decision or a live crossing-safety verdict.
NBI record plate
Structure MT:P00010003+05341
INTERSTATE-ERA · STEEL · LONG-SPAN-RUN · TIED-CTRL · HEAVY-ADT · LIGHT-LOAD · CAT-FAIR
- INTERSTATE-ERA 1950–1979
- STEEL Steel
- LONG-SPAN-RUN 6 spans
- TIED-CTRL Tied control
- HEAVY-ADT Heavy ADT
- LIGHT-LOAD Light load
- CAT-FAIR Fair
Inspection-sheet codes from this record’s year, material family, spans, controlling component, ADT, inventory load, and NBI category, not a live closure verdict.
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.
How 15TH ST N-US 87 compares
Age against the county: built in 1962, earlier than 95 of Cascade's 185 bridges with a recorded construction year (51%), against a county median build year of 1966. Age is not a defect on its own, but it is the population from which future Poor ratings are drawn.
Live comparison across Montana bridges with a recorded inventory load rating (5,144 of 5,224 rated).
15TH ST N-US 87 vs every rated Montana bridge
Inventory load rating (metric tons), FHWA NBI, this state
17 Top 91% higher than 9% of 5,144 bridges
rated Montana bridges, bucketed by value
Each bar is a band; taller bars hold more bridges. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source FHWA National Bridge Inventory · August 2026
Condition Ratings
Full 0–9 scale + sufficiency-rating breakdown: how condition ratings work.
Reported 0–9 component ratings from the FHWA NBI. The highlighted component is the lowest reported input to this record’s current condition category; it is not a closure or live crossing-safety decision.
Cascade inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 185 bridges in this county. Orthogonal to this structure's component profile above: a county catalog share, not a live crossing-safety verdict.
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
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.
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗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.
Share this inspection record
Send this source-bounded record or download its data card. An NBI condition category is not a closure or live crossing-safety verdict.
Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. Component ratings, ADT, and condition category on this page are copied from the NBI record for this structure; no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2024 NBI release. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.