STATE ROUTE 20
over SUTTER BYPASS
03-SUT-020-4.22, Sutter County, California
Condition
PoorYear Built
1938
Daily Traffic
7,600
Length
415 ft
About This Bridge
STATE ROUTE 20 carries traffic over SUTTER BYPASS in Sutter County, California. Built in 1938, this structure is 88 years old, making it a historic structure that has served the community for generations. The bridge features concrete continuous construction with a slab design, a combination chosen by engineers to meet the specific requirements of this crossing.
Approximately 7,600 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.
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 415 feet, this structure falls within the typical range requiring standard inspection procedures conducted by certified bridge inspectors.
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
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.
Deck Condition
Good
Superstructure
Good
Substructure
Poor
Channel & Protection
Satisfactory
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 substructure rating of 4 reflects significant wear in piers, abutments, or foundations.
For a structure built in 1938, 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 11 miles, underscoring the importance of maintaining this crossing.
Bridge Details
Concrete Continuous is the primary structural material, which influences maintenance requirements and expected lifespan. The slab 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 16,818 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.
7,600
Avg Daily Traffic (2009)
Vehicles per day crossing this bridge
—
Truck Traffic
Commercial vehicle percentage
11,524
Projected Future ADT
Estimated future demand
This bridge carries approximately 7,600 vehicles per day, translating to roughly 2,774,000 crossings annually. Lower traffic volumes generally result in less structural wear over time.
Traffic projections estimate future volumes of 11,524 vehicles daily, a 52% 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
3.6 tons
Maximum allowable load for special permits
Inventory Rating
2.2 tons
Load level for normal traffic
The operating rating of 3.6 tons represents the absolute maximum load this bridge can carry under controlled conditions with special permits. The inventory rating of 2.2 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
Status Changes
- Exited poor condition in 2021
- No longer structurally deficient as of 2021
- Entered poor condition in 2023
- Became structurally deficient in 2023
Data: 2020-2024 FHWA National Bridge Inventory
Location
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40.100833, -122.736389
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.