Structure 840 125 01950 · Multnomah County, OR

HWY 100 over Viaduct

Carries HWY 100 over Viaduct, 0.2 Mi W Multnomah Falls.

Overall conditionPoor

Set by its lowest-rated component: Superstructure at 4 of 9.

How ratings work
Deck6/9 · Satisfactory
Superstructuresets the rating4/9 · Poor
Substructure6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT402 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 4/9 · sets the ratingSubstructure 6/9

402 ft end to end, longest span 20 ft: about 6 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 slab bridge.

Built1914112 years old
Length401.9 ft122.5 m
Daily traffic901counted 2022
Last inspectedSeptember 2024every 12 months

Location

StateOregon
CountyMultnomah
Location0.2 Mi W Multnomah Falls
CarriesHWY 100
CrossesViaduct
Coordinates45.57710, -122.12100

Physical Characteristics

MaterialConcrete Continuous
DesignSlab
Total Length401.9 ft (122.5 m)
Max Span20.0 ft (6.1 m)
Deck Width20.0 ft (6.1 m)
Deck Area747.2 sq m
Main Spans20
Year Built1914

Traffic

Avg Daily Traffic901 (2022)
Truck Traffic4%
Lanes On Bridge2

Inspection & Ownership

Last InspectionSeptember 2024
Inspection FrequencyEvery 12 months
OwnerState Highway Agency
Historical SignificanceBridge is on the National Register of Historic Places
Scour CriticalNot applicable
Structure Number00840 125 01950

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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