Structure 35 0089 · San Mateo County, CA

Millbrae Avenue over U.s. Highway 101

Carries Millbrae Avenue over U.s. Highway 101, 04-sm-101-17.95-mlbr.

Overall conditionFair

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

How ratings work
Decksets the rating5/9 · Fair
Superstructure7/9 · Good
Substructure7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT815 FT OVERALL100 FT0ELEVATION · LENGTHS TO SCALE
Deck 5/9 · sets the ratingSuperstructure 7/9Substructure 7/9

815 ft end to end, longest span 75 ft: about 2.3 football fields. 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 multi-beam bridge.

Built1947rebuilt 1976
Length815.3 ft248.5 m
Daily traffic53,747counted 1999
Last inspectedApril 2023every 24 months

Location

StateCalifornia
CountySan Mateo
Location04-sm-101-17.95-mlbr
CarriesMillbrae Avenue
CrossesU.s. Highway 101
Coordinates37.60184, -122.38143

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length815.3 ft (248.5 m)
Max Span75.5 ft (23 m)
Deck Width81.4 ft (24.8 m)
Deck Area6162.8 sq m
Main Spans14
Year Built1947 (reconstructed 1976)

Traffic

Avg Daily Traffic53,747 (1999)
Truck Traffic5%
Lanes On Bridge5
Lanes Under Bridge12

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 Number35 0089

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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