US Bridges

SR 503 over Rock CR

Fair

Cowlitz County, Washington · 5.4 N JCT SR 503 Spur · Structure no. 0014654A0000000

Built
1996
29 years old
Condition
Fair
inspected April 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
418 ft
3 main spans
Daily traffic
1,700
2023 count
Owner
State
State Highway Agency

About this bridge

SR 503 over Rock CR is a steel continuous stringer/multi-beam or girder carrying SR 503 over Rock CR in Cowlitz County, Washington. It was built in 1996, so it is 29 years old, younger than the Washington average of 49.8 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 1,700 vehicles a day, roughly 12% of them trucks, projected to reach 1,659 by 2039. The structure is 418 ft (127.4 m) long and 35 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesSR 503
CrossesRock CR
Location5.4 N JCT SR 503 Spur
RouteState Highway 503
CountyCowlitz County
StateWashington
Coordinates45.99475, -122.45899
Functional classRural Minor Arterial

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionApril 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations on dry land well above flood water elevations
Structural evaluation7: Better than present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating61.9 US tons
Inventory rating37 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 25 or greater
Structure length418 ft (127.4 m)
Longest span158 ft (48.2 m)
Deck width35 ft (10.7 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,700 (2023)
Projected traffic1,659 by 2039
Trucks12%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.8 mi (159 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$7.3 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 503 over Rock CR built?

It was built in 1996, making it 29 years old in 2025.

What condition is SR 503 over Rock CR 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 April 2024.

How much traffic does SR 503 over Rock CR carry?

About 1,700 vehicles per day (2023 count), of which roughly 12% are trucks.

How long is SR 503 over Rock CR?

The structure is 418 ft (127.4 m) long with a longest span of 158 ft (48.2 m) and a deck 35 ft wide.

Who owns SR 503 over Rock CR?

It is owned by the State Highway Agency.