Structure 271 · Yukon-Koyukuk County, AK

Dalton Highway over Yukon River

Carries Dalton Highway over Yukon River, Mile Point 55.8.

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
SEMI-TRUCK · 72 FT2,295 FT OVERALL500 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 6/9 · sets the rating

2,295 ft end to end, longest span 410 ft: about 6.4 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 an orthotropic-deck bridge.

Built197551 years old
Length2294.9 ft699.5 m
Daily traffic140counted 2020
Last inspectedJuly 2024every 24 months

Location

StateAlaska
CountyYukon-Koyukuk
LocationMile Point 55.8
CarriesDalton Highway
CrossesYukon River
Coordinates65.87598, -149.72188

Physical Characteristics

MaterialSteel Continuous
DesignOrthotropic
Total Length2294.9 ft (699.5 m)
Max Span410.1 ft (125 m)
Deck Width30.8 ft (9.4 m)
Deck Area6575.3 sq m
Main Spans6
Year Built1975

Traffic

Avg Daily Traffic140 (2020)
Truck Traffic61%
Lanes On Bridge2

Inspection & Ownership

Last InspectionJuly 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical5 — Stable for scour
Structure Number0271

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.