Structure 20C0495 · Sonoma County, CA

4th ST East over Nathanson Creek

Carries 4th ST East over Nathanson Creek, 0.1 Mi N Of E Napa ST.

Overall conditionFair

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

How ratings work
Superstructuresets the rating5/9 · Fair
Substructure7/9 · Good
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT35 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck not ratedSuperstructure 5/9 · sets the ratingSubstructure 7/9

35 ft end to end. Lengths and the car 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 deck arch.

Built1914112 years old
Length35.1 ft10.7 m
Daily traffic2,100counted 2015
Last inspectedJune 2023every 24 months

Location

StateCalifornia
CountySonoma
Location0.1 Mi N Of E Napa ST
Carries4th ST East
CrossesNathanson Creek
Coordinates38.29251, -122.44965

Physical Characteristics

MaterialConcrete
DesignArch - Deck
Total Length35.1 ft (10.7 m)
Max Span29.9 ft (9.1 m)
Deck Width33.1 ft (10.1 m)
Deck Area108.1 sq m
Main Spans1
Year Built1914

Traffic

Avg Daily Traffic2,100 (2015)
Truck Traffic1%
Lanes On Bridge2

Inspection & Ownership

Last InspectionJune 2023
Inspection FrequencyEvery 24 months
OwnerCity/Municipal Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number20C0495

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.

Nearby Bridges