OLD HWY 10 W

over CLARK FORK 054

3M W ALBERTON, Mineral County, Montana

Condition

Poor

Year Built

1932

Daily Traffic

349

Length

52 ft

About This Bridge

OLD HWY 10 W carries traffic over CLARK FORK 054 in Mineral County, Montana. Built in 1932, this structure is 94 years old, making it a historic structure that has served the community for generations. The bridge features steel construction with a truss - deck design, a combination chosen by engineers to meet the specific requirements of this crossing.

Approximately 349 vehicles cross this bridge daily, indicating lower traffic volumes common for local roads and rural routes. While traffic is lighter, these bridges still serve essential community transportation needs. Commercial trucks account for 3% of all crossings. This proportion of commercial traffic is typical for this roadway classification and is factored into the bridge's design load ratings.

The bridge is currently rated in poor condition based on federal inspection criteria established by the Federal Highway Administration. It is classified as structurally deficient, meaning one or more components have received a rating of 4 or below on the 0-9 scale. This designation indicates significant deterioration that warrants attention, though the bridge remains safe for travel within its posted limits. Structurally deficient does not mean unsafe—rather, it signals that repairs or replacement should be prioritized in transportation planning. With a total length of 52 feet, this is a shorter span typical of local road crossings, often carrying traffic over small streams, drainage channels, or other roadways.

Steel bridges provide high strength-to-weight ratios, making them suitable for longer spans. However, they require ongoing protection against corrosion through painting or weathering steel designs. Inspectors pay close attention to connection points, fatigue cracking, and coating condition.

Federal law requires that all highway bridges be inspected at least every 24 months by qualified inspectors following the National Bridge Inspection Standards (NBIS). Some bridges with known issues or unusual characteristics may be inspected more frequently. Inspection data is reported to the National Bridge Inventory, a database maintained by the Federal Highway Administration that tracks the condition of all public highway bridges in the United States. This bridge data is sourced from that federal database and reflects the most recent available inspection results.

Condition Ratings

Structurally Deficient

This bridge has one or more component ratings of 4 or below, indicating significant deterioration that requires attention. The bridge remains safe for travel but may have load restrictions.

4

Deck Condition

Poor

5

Superstructure

Fair

6

Substructure

Satisfactory

8

Channel & Protection

Very Good

4

Lowest Rating

Determines condition category

NBI condition ratings range from 0 (failed) to 9 (excellent). Ratings of 4 or below are considered poor. The overall condition category is determined by the lowest individual component rating.

The deck rating of 4 indicates advanced deterioration affecting the driving surface.

For a structure built in 1932, the current condition reflects the cumulative effects of age, traffic, and environmental exposure. If this bridge were closed, traffic would face a detour of approximately 7 miles, underscoring the importance of maintaining this crossing.

Bridge Details

Steel is the primary structural material, which influences maintenance requirements and expected lifespan. The truss - deck design was selected based on span requirements, load capacity needs, and site conditions at the time of construction. Maintenance responsibility falls to State Highway Agency.

Construction

Year Built1932
MaterialSteel
Design TypeTruss - Deck
OwnerState Highway Agency

Dimensions

Total Length52 ft (15.8 m)
Max Span24 ft (7.3 m)
Deck Width3 ft
Deck Area1,311 sq ft

Span dimensions affect structural design choices and load distribution. The deck area of 1,311 sq ft determines surface maintenance scope.

Classification

Route TypeCounty Road
Route Number3117
Lanes On Bridge2
Lanes Under Bridge

Status

Toll BridgeNo
Historical SignificanceNot eligible
Scour CriticalNo
Detour Length7 mi (11 km)

Traffic Data

Traffic volume data helps engineers assess bridge wear patterns and plan maintenance schedules. Average Daily Traffic (ADT) counts are updated periodically and represent typical weekday usage.

349

Avg Daily Traffic (2022)

Vehicles per day crossing this bridge

3%

Truck Traffic

Commercial vehicle percentage

373

Projected Future ADT

Estimated future demand

This bridge carries approximately 349 vehicles per day, translating to roughly 127,385 crossings annually. Lower traffic volumes generally result in less structural wear over time.

Commercial trucks comprise 3% of traffic. Heavy vehicles cause disproportionate wear—a single fully loaded truck can have the impact of thousands of passenger cars on bridge deck surfaces.

Traffic projections estimate future volumes of 373 vehicles daily, a 7% increase from current levels. These projections inform capacity planning and potential upgrade requirements.

Load Ratings

Load ratings determine what weight this bridge can safely support. These values are critical for routing heavy vehicles and issuing overweight permits.

Operating Rating

2.5 tons

Maximum allowable load for special permits

Inventory Rating

1.5 tons

Load level for normal traffic

The operating rating of 2.5 tons represents the absolute maximum load this bridge can carry under controlled conditions with special permits. The inventory rating of 1.5 tons is the safe load limit for everyday traffic without restrictions. These relatively low ratings may result in posted weight limits or route restrictions for heavy vehicles.

5-Year Condition Trend

Stable

Condition has remained relatively stable since 2020

Data: 2020-2024 FHWA National Bridge Inventory

Location

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47.643889, -115.711944

Identification

Structure NumberL31170000+02001
NBI IDMT-L31170000+02001
State FIPS30
County FIPS061

Explore More

Data Source: Federal Highway Administration (FHWA) National Bridge Inventory 2024

Bridge inspection data is typically updated every 24 months. Conditions may have changed since the last inspection.

“Structurally deficient” does not mean a bridge is unsafe or likely to collapse. It indicates that one or more key structural elements are in poor or worse condition. Bridges are inspected regularly and may have load restrictions in place.

This data is for informational purposes only and should not be used for route clearance or vehicle weight decisions.

OLD HWY 10 W over CLARK FORK 054 | Montana