US Bridges

SR 300 over Mission Creek

Fair

Mason County, Washington · 0.3 E State Park · Structure no. 0007342A0000000

Built
1963
62 years old
Condition
Fair
inspected February 2024
Type
Slab
Wood or Timber
Length
51 ft
3 main spans
Daily traffic
7,374
2023 count
Owner
State
State Highway Agency

About this bridge

SR 300 over Mission Creek is a wood or timber slab carrying SR 300 over Mission Creek in Mason County, Washington. It was built in 1963, so it is 62 years old, older 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 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 7,374 vehicles a day, roughly 6% of them trucks, projected to reach 9,750 by 2039. The structure is 51 ft (15.5 m) long and 32 ft wide. If it were closed, the detour would be 18 mi (29 km).

Location

Open in Google Maps
CarriesSR 300
CrossesMission Creek
Location0.3 E State Park
RouteState Highway 300
CountyMason County
StateWashington
Coordinates47.43192, -122.87594
Functional classRural Major 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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
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 inspectionFebruary 2024
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 geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating41 US tons
Inventory rating30 US tons

Structure

Structure typeSlab
MaterialWood or Timber
DeckWood or timber
Main spans3
Design loadHS 20
Structure length51 ft (15.5 m)
Longest span17 ft (5.2 m)
Deck width32 ft (9.7 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic7,374 (2023)
Projected traffic9,750 by 2039
Trucks6%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed18 mi (29 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$727,000 (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 300 over Mission Creek built?

It was built in 1963, making it 62 years old in 2025.

What condition is SR 300 over Mission 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 February 2024.

How much traffic does SR 300 over Mission Creek carry?

About 7,374 vehicles per day (2023 count), of which roughly 6% are trucks.

How long is SR 300 over Mission Creek?

The structure is 51 ft (15.5 m) long with a longest span of 17 ft (5.2 m) and a deck 32 ft wide.

Who owns SR 300 over Mission Creek?

It is owned by the State Highway Agency.