Structure 20 0184R · Sonoma County, CA

US Highway 101 NB over Windsor Lane

Carries US Highway 101 NB over Windsor Lane, 04-son-101-29.35.

Overall conditionFair

Set by its lowest-rated component: Deck at 5 of 9.

How ratings work
Decksets the rating5/9 · Fair
Superstructure6/9 · Satisfactory
Substructure7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT304 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 5/9 · sets the ratingSuperstructure 6/9Substructure 7/9

304 ft end to end, longest span 84 ft: about 4 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 box-beam bridge.

Built196264 years old
Length304.1 ft92.7 m
Daily traffic22,750counted 2015
Last inspectedApril 2023every 24 months

Location

StateCalifornia
CountySonoma
Location04-son-101-29.35
CarriesUS Highway 101 NB
CrossesWindsor Lane
Coordinates38.54648, -122.80757

Physical Characteristics

MaterialConcrete Continuous
DesignBox Beam - Multiple
Total Length304.1 ft (92.7 m)
Max Span84.0 ft (25.6 m)
Deck Width39.7 ft (12.1 m)
Deck Area1121.7 sq m
Main Spans4
Year Built1962

Traffic

Avg Daily Traffic22,750 (2015)
Truck Traffic15%
Lanes On Bridge2
Lanes Under Bridge6

Inspection & Ownership

Last InspectionApril 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number20 0184R

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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