US Bridges

Co. Rd. 90100 over Decker Creek

Fair

Mason County, Washington · 6.4 MI So Matlock · Structure no. 086195000000000

Built
1996
29 years old
Condition
Fair
inspected April 2023
Type
Arch - Thru
Wood or Timber
Length
354 ft
1 main span
Daily traffic
588
2017 count
Owner
County
County Highway Agency

About this bridge

Co. Rd. 90100 over Decker Creek is a wood or timber arch - thru carrying Co. Rd. 90100 over Decker Creek in Mason 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 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 588 vehicles a day, roughly 20% of them trucks, projected to reach 800 by 2037. The structure is 354 ft (107.9 m) long and 33 ft wide. If it were closed, the detour would be 21.1 mi (34 km).

Location

Open in Google Maps
CarriesCo. Rd. 90100
CrossesDecker Creek
Location6.4 MI So Matlock
RouteCounty Highway 90100
CountyMason County
StateWashington
Coordinates47.15583, -123.465
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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating38 US tons
Inventory rating28 US tons

Structure

Structure typeArch - Thru
MaterialWood or Timber
DeckWood or timber
Main spans1 (+3 approach)
Design loadH 20
Structure length354 ft (107.9 m)
Longest span150 ft (45.7 m)
Deck width33 ft (10.2 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deck18 ft (5.5 m)

Traffic and service

Average daily traffic588 (2017)
Projected traffic800 by 2037
Trucks20%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed21.1 mi (34 km)
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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$35,000 (2070 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Co. Rd. 90100 over Decker Creek built?

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

What condition is Co. Rd. 90100 over Decker 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 April 2023.

How much traffic does Co. Rd. 90100 over Decker Creek carry?

About 588 vehicles per day (2017 count), of which roughly 20% are trucks.

How long is Co. Rd. 90100 over Decker Creek?

The structure is 354 ft (107.9 m) long with a longest span of 150 ft (45.7 m) and a deck 33 ft wide.

Who owns Co. Rd. 90100 over Decker Creek?

It is owned by the County Highway Agency.