Structure 27 0119 · Marin County, CA

U.s. Highway 101 over San Antonio Creek

Carries U.s. Highway 101 over San Antonio Creek, 04-mrn-101-27.53.

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 overall6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT510 FT OVERALL100 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 7/9

510 ft end to end, longest span 155 ft: about 7 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.

Built20197 years old
Length509.8 ft155.4 m
Daily traffic96,600counted 2017
Last inspectedMay 2023every 24 months

Location

StateCalifornia
CountyMarin
Location04-mrn-101-27.53
CarriesU.s. Highway 101
CrossesSan Antonio Creek
Coordinates38.18367, -122.60086

Physical Characteristics

MaterialPrestressed Concrete Continuous
DesignBox Beam - Multiple
Total Length509.8 ft (155.4 m)
Max Span154.9 ft (47.2 m)
Deck Width122.4 ft (37.3 m)
Deck Area5796.4 sq m
Main Spans4
Year Built2019

Traffic

Avg Daily Traffic96,600 (2017)
Truck Traffic5%
Lanes On Bridge4

Inspection & Ownership

Last InspectionMay 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number27 0119

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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