US Bridges

Project Access over Bonneville Dam

Fair

Multnomah County, Oregon · Tanner Creek Spur Bridge · Structure no. CEPNPPOR000BD04

Built
1907
118 years old
Condition
Fair
inspected September 2024
Type
Girder and Floorbeam System
Steel
Length
100 ft
1 main span
Daily traffic
20
2024 count
Owner
Federal
Corps of Engineers (Civil)

About this bridge

Project Access over Bonneville Dam is a steel girder and floorbeam system carrying Project Access over Bonneville Dam in Multnomah County, Oregon. It was built in 1907, so it is 118 years old, older than the Oregon average of 49.9 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 20 vehicles a day, roughly 10% of them trucks, projected to reach 20 by 2044. The structure is 100 ft (30.5 m) long and 16 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesProject Access
CrossesBonneville Dam
LocationTanner Creek Spur Bridge
RouteFederal Lands Road 0
CountyMultnomah County
StateOregon
Coordinates45.63252, -121.96045
Functional classRural Local

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourCountermeasures installed to correct a previously existing problem
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating92.5 US tons
Inventory rating71.4 US tons

Structure

Structure typeGirder and Floorbeam System
MaterialSteel
DeckWood or timber
Main spans1
Design loadRailroad
Structure length100 ft (30.5 m)
Longest span98 ft (29.9 m)
Deck width16 ft (5 m)
Roadway width9 ft (2.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic20 (2024)
Projected traffic20 by 2044
Trucks10%
Lanes on structure1
Traffic directionOne-way traffic
CarriesHighway
CrossesOther
Detour if closed123.7 mi (199 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCorps of Engineers (Civil)
Maintained byCorps of Engineers (Civil)
Historic statusHistorical significance not determinable at this time
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$162,000 (2024 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Project Access over Bonneville Dam built?

It was built in 1907, making it 118 years old in 2025.

What condition is Project Access over Bonneville Dam in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in September 2024.

How much traffic does Project Access over Bonneville Dam carry?

About 20 vehicles per day (2024 count), of which roughly 10% are trucks.

How long is Project Access over Bonneville Dam?

The structure is 100 ft (30.5 m) long with a longest span of 98 ft (29.9 m) and a deck 16 ft wide.

Who owns Project Access over Bonneville Dam?

It is owned by the Corps of Engineers (Civil).