US Bridges

HWY 100 over Rock Creek

FairPosted for load

Wasco County, Oregon · West of Mosier · Structure no. 65C63 407000030

Built
1930
95 years old, rebuilt 1995
Condition
Fair
inspected May 2023
Type
Tee Beam
Concrete Continuous
Length
45 ft
2 main spans
Daily traffic
2,209
2022 count
Owner
State
State Highway Agency

About this bridge

HWY 100 over Rock Creek is a concrete continuous tee beam carrying HWY 100 over Rock Creek in Wasco County, Oregon. It was built in 1930 and reconstructed in 1995, so it is 95 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. Its operating status is: posted for load restriction.

It carries about 2,209 vehicles a day, roughly 8% of them trucks, projected to reach 2,400 by 2042. The structure is 45 ft (13.7 m) long and 23 ft wide. If it were closed, the detour would be 10.6 mi (17 km).

Location

Open in Google Maps
CarriesHWY 100
CrossesRock Creek
LocationWest of Mosier
RouteState Highway 30
CountyWasco County
StateOregon
Coordinates45.68488, -121.40476
Functional classRural Minor Collector

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.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusPosted for load 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 geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating31.7 US tons
Inventory rating24.5 US tons

Structure

Structure typeTee Beam
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadH 15
Structure length45 ft (13.7 m)
Longest span21 ft (6.4 m)
Deck width23 ft (6.9 m)
Roadway width19 ft (5.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,209 (2022)
Projected traffic2,400 by 2042
Trucks8%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed10.6 mi (17 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusListed on the National Register of Historic Places
Work proposedWidening of existing bridge without deck rehabilitation
Estimated improvement cost$231,000
NavigationNo navigation control on waterway

Frequently asked questions

When was HWY 100 over Rock Creek built?

It was built in 1930, making it 95 years old in 2025. It was reconstructed in 1995.

What condition is HWY 100 over Rock Creek 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 May 2023.

How much traffic does HWY 100 over Rock Creek carry?

About 2,209 vehicles per day (2022 count), of which roughly 8% are trucks.

How long is HWY 100 over Rock Creek?

The structure is 45 ft (13.7 m) long with a longest span of 21 ft (6.4 m) and a deck 23 ft wide.

Who owns HWY 100 over Rock Creek?

It is owned by the State Highway Agency.