US Bridges

Old Tv HWY #47 over Gaston Slough

Fair

Washington County, Oregon · 010 W HWY #47 · Structure no. 671405C02902600

Built
1934
91 years old
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
58 ft
3 main spans
Daily traffic
568
2020 count
Owner
County
County Highway Agency

About this bridge

Old Tv HWY #47 over Gaston Slough is a wood or timber stringer/multi-beam or girder carrying Old Tv HWY #47 over Gaston Slough in Washington County, Oregon. It was built in 1934, so it is 91 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 6 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 568 vehicles a day, roughly 5% of them trucks, projected to reach 643 by 2025. The structure is 58 ft (17.7 m) long and 27 ft wide.

Location

Open in Google Maps
CarriesOld Tv HWY #47
CrossesGaston Slough
Location010 W HWY #47
RouteCounty Highway C1204
CountyWashington County
StateOregon
Coordinates45.44164, -123.1424
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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy3: Basically intolerable, requiring high priority of corrective action
Approach roadway alignment8: Equal to present desirable criteria
Operating rating27.1 US tons
Inventory rating21.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans3
Design loadH 20
Structure length58 ft (17.7 m)
Longest span19 ft (5.8 m)
Deck width27 ft (8.3 m)
Roadway width24 ft (7.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic568 (2020)
Projected traffic643 by 2025
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesRelief for waterway
Detour if closed—
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Old Tv HWY #47 over Gaston Slough built?

It was built in 1934, making it 91 years old in 2025.

What condition is Old Tv HWY #47 over Gaston Slough 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 2023.

How much traffic does Old Tv HWY #47 over Gaston Slough carry?

About 568 vehicles per day (2020 count), of which roughly 5% are trucks.

How long is Old Tv HWY #47 over Gaston Slough?

The structure is 58 ft (17.7 m) long with a longest span of 19 ft (5.8 m) and a deck 27 ft wide.

Who owns Old Tv HWY #47 over Gaston Slough?

It is owned by the County Highway Agency.