US 101

over CHEHALIS RIVER

0.2 N JCT SR 105, Grays Harbor County, Washington

Condition

Poor

Year Built

1955

Daily Traffic

25,602

Length

264 ft

About This Bridge

US 101 carries traffic over CHEHALIS RIVER in Grays Harbor County, Washington. Built in 1955, this structure is 71 years old, placing it among the older bridges still in active service. The bridge features steel construction with a movable - bascule design, a combination chosen by engineers to meet the specific requirements of this crossing.

Approximately 25,602 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 5% 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 264 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

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.

6

Deck Condition

Satisfactory

4

Superstructure

Poor

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 superstructure rating of 4 shows advanced deterioration in beams or girders.

For a structure built in 1955, the current condition reflects the cumulative effects of age, traffic, and environmental exposure. High traffic volumes on a bridge in fair or poor condition typically elevate its priority for rehabilitation or replacement in state transportation planning. If this bridge were closed, traffic would face a detour of approximately 25 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

Year Built1955
MaterialSteel
Design TypeMovable - Bascule
OwnerState Highway Agency

Dimensions

Total Length264 ft (80.4 m)
Max Span34 ft (10.4 m)
Deck Width7 ft
Deck Area16,404 sq ft

Span dimensions affect structural design choices and load distribution. The deck area of 16,404 sq ft determines surface maintenance scope.

Classification

Route TypeUS Highway
Route Number101
Lanes On Bridge4
Lanes Under Bridge5

Status

Toll BridgeNo
Historical SignificanceOn National Register of Historic Places
Scour Critical3
Detour Length25 mi (40 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.

25,602

Avg Daily Traffic (2022)

Vehicles per day crossing this bridge

5%

Truck Traffic

Commercial vehicle percentage

31,924

Projected Future ADT

Estimated future demand

This bridge carries approximately 25,602 vehicles per day, translating to roughly 9,344,730 crossings annually. This moderate traffic level is typical for regional connectors.

Commercial trucks comprise 5% 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 31,924 vehicles daily, a 25% 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

2.6 tons

Maximum allowable load for special permits

Inventory Rating

2.0 tons

Load level for normal traffic

The operating rating of 2.6 tons represents the absolute maximum load this bridge can carry under controlled conditions with special permits. The inventory rating of 2.0 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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47.372222, -124.355556

Identification

Structure Number0004386A0000000
NBI IDWA-0004386A0000000
State FIPS53
County FIPS027

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.

US 101 over CHEHALIS RIVER | Washington