Structure 12775 · Ada County, ID

Stp 7343;main ST over Boise River

Carries Stp 7343;main ST over Boise River, In Boise;main St. Wbl.

Overall conditionFair

Set by its lowest-rated component: Deck and Substructure at 6 of 9.

How ratings work
Decksets the rating6/9 · Satisfactory
Superstructure7/9 · Good
Substructuresets the rating6/9 · Satisfactory
Channelnot part of overall6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT284 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9 · sets the ratingSuperstructure 7/9Substructure 6/9 · sets the rating

284 ft end to end, longest span 69 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 multi-beam bridge.

Built196561 years old
Length284.1 ft86.6 m
Daily traffic14,000counted 2023
Last inspectedSeptember 2024every 48 months

Location

StateIdaho
CountyAda
LocationIn Boise;main St. Wbl
CarriesStp 7343;main ST
CrossesBoise River
Coordinates43.62033, -116.23136

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length284.1 ft (86.6 m)
Max Span68.9 ft (21 m)
Deck Width58.4 ft (17.8 m)
Deck Area1541.5 sq m
Main Spans4
Year Built1965

Traffic

Avg Daily Traffic14,000 (2023)
Truck Traffic5%
Lanes On Bridge3

Inspection & Ownership

Last InspectionSeptember 2024
Inspection FrequencyEvery 48 months
OwnerCounty Highway Agency
Historical SignificanceHistorical significance is not determined
Scour Critical8 — Stable, low risk
Structure Number000000000012775

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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