US Bridges

Mountain Loop HWY over Black Creek

Fair

Snohomish County, Washington · 14.3 E JCT SR 92 · Structure no. 083288000000000

Built
1952
73 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Concrete
Length
91 ft
3 main spans
Daily traffic
1,932
2022 count
Owner
County
County Highway Agency

About this bridge

Mountain Loop HWY over Black Creek is a concrete stringer/multi-beam or girder carrying Mountain Loop HWY over Black Creek in Snohomish County, Washington. It was built in 1952, so it is 73 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 1,932 vehicles a day, roughly 7% of them trucks, projected to reach 2,000 by 2045. The structure is 91 ft (27.6 m) long and 30 ft wide. If it were closed, the detour would be 93.8 mi (151 km).

Location

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CarriesMountain Loop HWY
CrossesBlack Creek
Location14.3 E JCT SR 92
RouteCounty Highway 98960
CountySnohomish County
StateWashington
Coordinates48.0718, -121.72506
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
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 inspectionAugust 2023
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 geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating52 US tons
Inventory rating31 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialConcrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length91 ft (27.6 m)
Longest span30 ft (9.2 m)
Deck width30 ft (9.1 m)
Roadway width26 ft (8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,932 (2022)
Projected traffic2,000 by 2045
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed93.8 mi (151 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$3.6 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Mountain Loop HWY over Black Creek built?

It was built in 1952, making it 73 years old in 2025.

What condition is Mountain Loop HWY over Black 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 August 2023.

How much traffic does Mountain Loop HWY over Black Creek carry?

About 1,932 vehicles per day (2022 count), of which roughly 7% are trucks.

How long is Mountain Loop HWY over Black Creek?

The structure is 91 ft (27.6 m) long with a longest span of 30 ft (9.2 m) and a deck 30 ft wide.

Who owns Mountain Loop HWY over Black Creek?

It is owned by the County Highway Agency.