US Bridges

SR 108 over Unt to Skookum Creek

Good

Mason County, Washington · 5.6 E JCT SR 8 · Structure no. 0019714B0000000

Built
2024
1 years old
Condition
Good
inspected June 2024
Type
Culvert
Concrete
Length
35 ft
1 main span
Daily traffic
3,581
2023 count
Owner
State
State Highway Agency

About this bridge

SR 108 over Unt to Skookum Creek is a concrete culvert carrying SR 108 over Unt to Skookum Creek in Mason County, Washington. It was built in 2024, so it is 1 years old, younger than the Washington average of 49.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 3,581 vehicles a day, roughly 17% of them trucks, projected to reach 5,410 by 2043. The structure is 35 ft (10.7 m) long and 47 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

CarriesSR 108
CrossesUnt to Skookum Creek
Location5.6 E JCT SR 8
RouteState Highway 108
Coordinates47.09709, -123.21336
Functional classRural Minor Arterial

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Channel and channel protection8 Very GoodNo problems noted.
Culvert8 Very GoodNo problems noted.
Last inspectionJune 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation8: Equal to present desirable criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating50.7 US tons
Inventory rating39.2 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans1
Design loadHL 93
Structure length35 ft (10.7 m)
Longest span35 ft (10.7 m)
Deck width47 ft (14.4 m)
Roadway width29 ft (8.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,581 (2023)
Projected traffic5,410 by 2043
Trucks17%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 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$515,000 (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 108 over Unt to Skookum Creek built?

It was built in 2024, making it 1 years old in 2025.

What condition is SR 108 over Unt to Skookum Creek in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in June 2024.

How much traffic does SR 108 over Unt to Skookum Creek carry?

About 3,581 vehicles per day (2023 count), of which roughly 17% are trucks.

How long is SR 108 over Unt to Skookum Creek?

The structure is 35 ft (10.7 m) long with a longest span of 35 ft (10.7 m) and a deck 47 ft wide.

Who owns SR 108 over Unt to Skookum Creek?

It is owned by the State Highway Agency.