Structure 13055A0000000 · Thurston County, WA

SR 507 over Nisqually River

Carries SR 507 over Nisqually River, 2.4 N Jct SR 510.

Overall conditionFair

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

How ratings work
Decksets the rating6/9 · Satisfactory
Superstructure7/9 · Good
Substructure7/9 · Good
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 7/9

284 ft end to end, longest span 110 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.

Built198739 years old
Length284.1 ft86.6 m
Daily traffic22,357counted 2023
Last inspectedSeptember 2023every 24 months

Location

StateWashington
CountyThurston
Location2.4 N Jct SR 510
CarriesSR 507
CrossesNisqually River
Coordinates46.93323, -122.56091

Physical Characteristics

MaterialPrestressed Concrete Continuous
DesignStringer/Multi-beam
Total Length284.1 ft (86.6 m)
Max Span109.9 ft (33.5 m)
Deck Width46.3 ft (14.1 m)
Deck Area1221.1 sq m
Main Spans3
Year Built1987

Traffic

Avg Daily Traffic22,357 (2023)
Truck Traffic5%
Lanes On Bridge3

Inspection & Ownership

Last InspectionSeptember 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical7 — Countermeasures installed
Structure Number0013055A0000000

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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