Hwy 105
over Old Youngs Bay
002 MI S ASTORIA, Clatsop County, Oregon
Condition
FairYear Built
1921
Daily Traffic
6,877
Length
185 ft
About This Bridge
Hwy 105 carries traffic over Old Youngs Bay in Clatsop County, Oregon. Built in 1921, this structure is 105 years old, making it a historic structure that has served the community for generations. The bridge features steel construction with a movable - bascule design, a combination chosen by engineers to meet the specific requirements of this crossing.
Approximately 6,877 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 15% 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 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 185 feet, this structure falls within the typical range requiring standard inspection procedures conducted by certified bridge inspectors.
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
Deck Condition
Satisfactory
Superstructure
Fair
Substructure
Fair
Channel & Protection
Good
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 5 indicates some deterioration that warrants monitoring but doesn't affect structural integrity.
For a structure built in 1921, this condition level is expected given the bridge's age and usage patterns. 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 movable - bascule 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
Dimensions
Span dimensions affect structural design choices and load distribution. The deck area of 5,737 sq ft determines surface maintenance scope.
Classification
Status
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.
6,877
Avg Daily Traffic (2020)
Vehicles per day crossing this bridge
15%
Truck Traffic
Commercial vehicle percentage
9,200
Projected Future ADT
Estimated future demand
This bridge carries approximately 6,877 vehicles per day, translating to roughly 2,510,105 crossings annually. Lower traffic volumes generally result in less structural wear over time.
Commercial trucks comprise 15% 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 9,200 vehicles daily, a 34% 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
1.8 tons
Maximum allowable load for special permits
Inventory Rating
1.4 tons
Load level for normal traffic
The operating rating of 1.8 tons represents the absolute maximum load this bridge can carry under controlled conditions with special permits. The inventory rating of 1.4 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
→StableCondition has remained relatively stable since 2020
Data: 2020-2024 FHWA National Bridge Inventory
Location
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46.383611, -124.311389
Identification
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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.