Structure 15 0024 · Colusa County, CA

State Route 20 over 7th ST Cnfr E Side Cnl

Carries State Route 20 over 7th ST Cnfr E Side Cnl, 03-col-020-r21.85.

Overall conditionGood

Set by its lowest-rated component: Deck and Superstructure and Substructure at 7 of 9.

How ratings work
Decksets the rating7/9 · Good
Superstructuresets the rating7/9 · Good
Substructuresets the rating7/9 · Good
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT343 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 7/9

343 ft end to end, longest span 121 ft: about 5 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.

Built197155 years old
Length342.8 ft104.5 m
Daily traffic5,800counted 2012
Last inspectedJanuary 2025every 24 months

Location

StateCalifornia
CountyColusa
Location03-col-020-r21.85
CarriesState Route 20
Crosses7th ST Cnfr E Side Cnl
Coordinates39.16471, -122.15422

Physical Characteristics

MaterialPrestressed Concrete Continuous
DesignBox Beam - Multiple
Total Length342.8 ft (104.5 m)
Max Span121.1 ft (36.9 m)
Deck Width42.0 ft (12.8 m)
Deck Area1337.6 sq m
Main Spans3
Year Built1971

Traffic

Avg Daily Traffic5,800 (2012)
Truck Traffic11%
Lanes On Bridge2
Lanes Under Bridge2

Inspection & Ownership

Last InspectionJanuary 2025
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number15 0024

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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