I 15 SBL

over SNAKE RIVER;BLACKFOOT BR

1.9 N. BLACKFOOT, Bingham County, Idaho

Condition

Fair

Year Built

2002

Daily Traffic

12,750

Length

83 ft

About This Bridge

I 15 SBL carries traffic over SNAKE RIVER;BLACKFOOT BR in Bingham County, Idaho. Built in 2002, this structure is 24 years old, representing modern engineering and construction standards. The bridge features prestressed concrete continuous construction with a stringer/multi-beam or girder design, a combination chosen by engineers to meet the specific requirements of this crossing.

Approximately 12,750 vehicles cross this bridge daily, representing moderate traffic volumes typical of important regional connectors. This level of usage requires regular monitoring to ensure continued safe operation. Commercial trucks account for 18% of all crossings. This heavy commercial usage significantly impacts structural wear, as a single fully-loaded truck can cause as much deck wear as thousands of passenger vehicles. Transportation planners factor this into maintenance scheduling and budget allocation.

The bridge is currently rated in fair condition based on federal inspection criteria established by the Federal Highway Administration. The structure meets current safety standards for its designated use and load capacity. With a total length of 83 feet, this is a shorter span typical of local road crossings, often carrying traffic over small streams, drainage channels, or other roadways.

The construction materials used in this bridge were selected based on engineering requirements, cost considerations, and local conditions at the time of construction.

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

6

Deck Condition

Satisfactory

7

Superstructure

Good

6

Substructure

Satisfactory

7

Channel & Protection

Good

6

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 fair condition rating of 6 indicates satisfactory condition with minor section loss or deterioration.

For a structure built in 2002, this condition level is expected given the bridge's age and usage patterns.

Bridge Details

Prestressed Concrete Continuous is the primary structural material, which influences maintenance requirements and expected lifespan. The stringer/multi-beam or girder 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 Built2002
MaterialPrestressed Concrete Continuous
Design TypeStringer/Multi-beam or Girder
OwnerState Highway Agency

Dimensions

Total Length83 ft (25.3 m)
Max Span12 ft (3.6 m)
Deck Width4 ft
Deck Area3,344 sq ft

Span dimensions affect structural design choices and load distribution. The deck area of 3,344 sq ft determines surface maintenance scope.

Classification

Route TypeInterstate
Route Number15
Lanes On Bridge2
Lanes Under Bridge

Status

Toll BridgeNo
Historical SignificanceNot determined
Scour Critical8
Detour Length1 mi (1 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.

12,750

Avg Daily Traffic (2022)

Vehicles per day crossing this bridge

18%

Truck Traffic

Commercial vehicle percentage

19,125

Projected Future ADT

Estimated future demand

This bridge carries approximately 12,750 vehicles per day, translating to roughly 4,653,750 crossings annually. This moderate traffic level is typical for regional connectors.

Commercial trucks comprise 18% 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. This high percentage of truck traffic may accelerate deterioration of deck surfaces and structural components.

Traffic projections estimate future volumes of 19,125 vehicles daily, a 50% 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

9.1 tons

Maximum allowable load for special permits

Inventory Rating

4.8 tons

Load level for normal traffic

The operating rating of 9.1 tons represents the absolute maximum load this bridge can carry under controlled conditions with special permits. The inventory rating of 4.8 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

Declining

Condition has declined by 1.0 rating points since 2020

Data: 2020-2024 FHWA National Bridge Inventory

Location

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43.850278, -113.273056

Identification

Structure Number000000000011491
NBI IDID-000000000011491
State FIPS16
County FIPS011

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.

I 15 SBL over SNAKE RIVER;BLACKFOOT BR | Idaho