OLD MIL. RR GRADE
Carrying OLD MIL. RR GRADE over SLOUGH BRIDGE
1.4N 3.1W CALDER, Shoshone, Idaho
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
OLD MIL. RR GRADE in Shoshone, Idaho sits above 4% of rated Idaho bridges on inventory load rating (15 t), while its 1912 build year is earlier than 97% of Shoshone's recorded-year cohort (260 bridges).
OLD MIL. RR GRADE in Shoshone, Idaho is rated Poor in the FHWA's 2024 National Bridge Inventory. Built in 1912, it carries 3 rated components on the inspecting agency's 0-9 scale, and its weakest reported component scores 4. The lowest applicable rating sets the federal condition category, so this Poor 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 ID:000000000037080
PRE-1950 · TIMBER · LONG-SPAN-RUN · TIED-CTRL · TRACE-ADT · LIGHT-LOAD · CAT-POOR
- PRE-1950 Pre-1950
- TIMBER Wood or timber
- LONG-SPAN-RUN 6 spans
- TIED-CTRL Tied control
- TRACE-ADT Trace ADT
- LIGHT-LOAD Light load
- CAT-POOR Poor
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: OLD MIL. RR GRADE
The OLD MIL. RR GRADE bridge in Shoshone, Idaho carries OLD MIL. RR GRADE over SLOUGH BRIDGE. It was built in 1912, making it 114 years old today. It was last reconstructed in 1991, extending its service life. The structure is built primarily of wood or timber and spans 6 sections, stretching 29.6 meters (97 feet) end to end. Daily traffic averages 15 vehicles, placing it in the lower-traffic tier of Idaho bridges. It is owned and maintained by County Highway Agency.
The latest FHWA inspection records show a deck rating of 4/9, superstructure at 6/9, substructure at 4/9. The weakest component sits in poor condition. Because at least one major component scores 4 or lower, this bridge falls in FHWA's Poor condition category. That category is not a closure order.
How OLD MIL. RR GRADE compares
Age against the county: built in 1912, earlier than 252 of Shoshone's 260 bridges with a recorded construction year (97%), against a county median build year of 1973. Age is not a defect on its own, but it is the population from which future Poor ratings are drawn.
Live comparison across Idaho bridges with a recorded inventory load rating (4,574 of 4,616 rated).
OLD MIL. RR GRADE vs every rated Idaho bridge
Inventory load rating (metric tons), FHWA NBI, this state
15 Top 96% higher than 4% of 4,574 bridges
rated Idaho 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.
Shoshone inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 260 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
- 1912
- Last Reconstructed
- 1991
- Material
- Wood or Timber
- Number of Spans
- 6
- Structure Length
- 29.6 m (97 ft)
- Deck Width
- 4.2 m (14 ft)
- Owner
- County Highway Agency
- Avg Daily Traffic
- 15 vehicles/day
- Structure Number
- 000000000037080
Condition Analysis
- • At 4/9, the deck (driving surface) is in poor shape, with advanced wear on file for this vintage.
- • The superstructure (beams and supports above the deck) is in fair condition (6/9), with minor deterioration that may require routine maintenance.
- • At 4/9, the substructure (piers and abutments) is in poor shape, with advanced wear on file for this vintage.
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗How to read this record
OLD MIL. RR GRADE 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 MIL. RR GRADE against other structures in Shoshone and across Idaho. Idaho 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 MIL. RR GRADE?
OLD MIL. RR GRADE in Shoshone, Idaho has a deck rating of 4/9, superstructure rating of 6/9, and substructure rating of 4/9 on the FHWA's 0–9 scale.
How often is OLD MIL. RR GRADE inspected?
OLD MIL. RR GRADE'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 15 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. OLD MIL. RR GRADE 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 MIL. RR GRADE?
OLD MIL. RR GRADE has an NBI inventory load rating of 14.5 metric tons.
Who is responsible for maintaining OLD MIL. RR GRADE?
OLD MIL. RR GRADE is owned and maintained by County Highway Agency.
How old is OLD MIL. RR GRADE and does age affect safety?
OLD MIL. RR GRADE was built in 1912, making it 114 years old and last reconstructed in 1991.
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.