Route 284
Carrying Route 284 over Canyon Ferry Spillway
14 mi E-NE of Helena MT, Lewis and Clark, Montana
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
Route 284 in Lewis and Clark, Montana is rated Fair in the FHWA's 2024 National Bridge Inventory.
Built in 1950, 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:MTA-CF-001
INTERSTATE-ERA · STEEL · LONG-SPAN-RUN · TIED-CTRL · LOCAL-ADT · HEAVY-LOAD · CAT-FAIR
- INTERSTATE-ERA 1950–1979
- STEEL Steel
- LONG-SPAN-RUN 4 spans
- TIED-CTRL Tied control
- LOCAL-ADT Local ADT
- HEAVY-LOAD Heavy 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: Route 284
The Route 284 bridge in Lewis and Clark, Montana carries Route 284 over Canyon Ferry Spillway. It was built in 1950, making it 76 years old today. The structure is built primarily of steel and spans 4 sections, stretching 70.2 meters (230 feet) end to end. Daily traffic averages 600 vehicles, placing it in the lower-traffic tier of Montana bridges. It is owned and maintained by Bureau of Reclamation.
The latest FHWA inspection records show a deck rating of 5/9, superstructure at 5/9, substructure at 6/9. The weakest component sits in fair condition. No reported major component scores in the Poor range under the current federal condition thresholds.
How Route 284 compares
Age against the county: built in 1950, earlier than 173 of Lewis and Clark's 200 bridges with a recorded construction year (87%), against a county median build year of 1978. 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).
Route 284 vs every rated Montana bridge
Inventory load rating (metric tons), FHWA NBI, this state
44 Top 8% higher than 92% 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.
Lewis and Clark inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 200 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
- 1950
- Material
- Steel
- Number of Spans
- 4
- Structure Length
- 70.2 m (230 ft)
- Deck Width
- 8.3 m (27 ft)
- Owner
- Bureau of Reclamation
- Avg Daily Traffic
- 600 vehicles/day
- Structure Number
- MTA-CF-001
Condition Analysis
- • The deck (driving surface) rates fair at 5/9, minor deterioration that routine maintenance should address.
- • At 5/9, the superstructure (beams and supports above the deck) shows fair condition, with minor wear flagged for upkeep.
- • At 6/9, 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 Route 284 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 Route 284 against other structures in Lewis and Clark 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 Route 284?
Route 284 in Lewis and Clark, Montana has a deck rating of 5/9, superstructure rating of 5/9, and substructure rating of 6/9 on the FHWA's 0–9 scale.
How often is Route 284 inspected?
Route 284'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 600 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. Route 284 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 Route 284?
Route 284 has an NBI inventory load rating of 44.1 metric tons.
Who is responsible for maintaining Route 284?
Route 284 is owned and maintained by Bureau of Reclamation.
How old is Route 284 and does age affect safety?
Route 284 was built in 1950, making it 76 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.
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.