Structure 4 0145 · Humboldt County, CA

US Highway 101 over S101-main On&off Ncrra

Carries US Highway 101 over S101-main On&off Ncrra, 01-hum-101-61.53-fta.

Overall conditionFair

Set by its lowest-rated component: Substructure at 6 of 9.

How ratings work
Deck7/9 · Good
Superstructure7/9 · Good
Substructuresets the rating6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT457 FT OVERALL100 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 6/9 · sets the rating

457 ft end to end, longest span 88 ft: about 6 semi-trucks nose to tail. Lengths and the semi-truck on the deck are drawn to the same scale. Each part is colored by its latest inspection rating. The inventory records lengths but not heights or the layout of the shorter spans, so those are drawn as typical for a tee-beam bridge.

Built1962rebuilt 1993
Length457.0 ft139.3 m
Daily traffic12,800counted 2009
Last inspectedAugust 2023every 24 months

Location

StateCalifornia
CountyHumboldt
Location01-hum-101-61.53-fta
CarriesUS Highway 101
CrossesS101-main On&off Ncrra
Coordinates40.59889, -124.16727

Physical Characteristics

MaterialConcrete Continuous
DesignTee Beam
Total Length457.0 ft (139.3 m)
Max Span87.9 ft (26.8 m)
Deck Width80.1 ft (24.4 m)
Deck Area3398.9 sq m
Main Spans6
Year Built1962 (reconstructed 1993)

Traffic

Avg Daily Traffic12,800 (2009)
Truck Traffic11%
Lanes On Bridge4
Lanes Under Bridge2

Inspection & Ownership

Last InspectionAugust 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number04 0145

How Bridge Ratings Work

Inspectors rate each major part of a bridge (the deck you drive on, the superstructure of beams that holds it up, and the substructure of piers and abutments beneath) on a 0–9 scale. A bridge's overall condition is its lowest of those ratings, so one deteriorated component makes the whole bridge "poor."

0Failed
1Imminent failure
2Critical
3Serious
4Poor
5Fair
6Satisfactory
7Good
8Very good
9Excellent
Good · lowest component 7–9
Fair · lowest component 5–6
Poor · lowest component 0–4

A poor rating is not a closure. It means the bridge is flagged for priority repair or replacement; bridges judged unsafe are closed or posted with weight limits. The waterway (channel) rating is reported, but it does not count toward the overall classification.

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