Structure 52608295 · Pennington County, SD

161st Avenue over Boxelder Ck

Carries 161st Avenue over Boxelder Ck, 0.6s New Underwood.

Overall conditionFair

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

How ratings work
Deck7/9 · Good
Superstructure7/9 · Good
Substructuresets the rating6/9 · Satisfactory
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT81 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 6/9 · sets the rating

81 ft end to end, longest span 39 ft. 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 tee-beam bridge.

Built197353 years old
Length81.0 ft24.7 m
Daily traffic780counted 2022
Last inspectedAugust 2023every 24 months

Location

StateSouth Dakota
CountyPennington
Location0.6s New Underwood
Carries161st Avenue
CrossesBoxelder Ck
Coordinates44.08849, -102.83418

Physical Characteristics

MaterialPrestressed Concrete
DesignTee Beam
Total Length81.0 ft (24.7 m)
Max Span39.0 ft (11.9 m)
Deck Width30.8 ft (9.4 m)
Deck Area232.2 sq m
Main Spans3
Year Built1973

Traffic

Avg Daily Traffic780 (2022)
Truck Traffic12%
Lanes On Bridge2

Inspection & Ownership

Last InspectionAugust 2023
Inspection FrequencyEvery 24 months
OwnerCounty Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number000000052608295

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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