Structure 629 · Anchorage County, AK

Seward Highway over Placer River Main Cross

Carries Seward Highway over Placer River Main Cross, Mile Point 77.5.

Overall conditionGood

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

How ratings work
Decksets the rating9/9 · Excellent
Superstructuresets the rating9/9 · Excellent
Substructuresets the rating9/9 · Excellent
Channelnot part of overall9/9 · Excellent
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT598 FT OVERALL100 FT0ELEVATION · LENGTHS TO SCALE
Deck 9/9Superstructure 9/9Substructure 9/9

598 ft end to end, longest span 116 ft: about 1.7 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 tee-beam bridge.

Built20233 years old
Length598.4 ft182.4 m
Daily traffic3,900counted 2020
Last inspectedAugust 2023every 24 months

Location

StateAlaska
CountyAnchorage
LocationMile Point 77.5
CarriesSeward Highway
CrossesPlacer River Main Cross
Coordinates60.81657, -148.98763

Physical Characteristics

MaterialPrestressed Concrete
DesignTee Beam
Total Length598.4 ft (182.4 m)
Max Span116.5 ft (35.5 m)
Deck Width66.3 ft (20.2 m)
Deck Area3684.5 sq m
Main Spans5
Year Built2023

Traffic

Avg Daily Traffic3,900 (2020)
Truck Traffic14%
Lanes On Bridge3

Inspection & Ownership

Last InspectionAugust 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number0629

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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