US Bridges

Mary M Knight RD over Dry Creek

Fair

Mason County, Washington · 0.15 W of Matlockbradyrd · Structure no. 082799000000000

Built
1970
55 years old
Condition
Fair
inspected April 2024
Type
Tee Beam
Concrete
Length
30 ft
1 main span
Daily traffic
148
2020 count
Owner
County
County Highway Agency

About this bridge

Mary M Knight RD over Dry Creek is a concrete tee beam carrying Mary M Knight RD over Dry Creek in Mason County, Washington. It was built in 1970, so it is 55 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 148 vehicles a day, roughly 15% of them trucks, projected to reach 210 by 2040. The structure is 30 ft (9.1 m) long and 21 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesMary M Knight RD
CrossesDry Creek
Location0.15 W of Matlockbradyrd
RouteCounty Highway 500
CountyMason County
StateWashington
Coordinates47.19856, -123.43728
Functional classRural Local

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 protection7 GoodSome minor problems.
Last inspectionApril 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 geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating55 US tons
Inventory rating33 US tons

Structure

Structure typeTee Beam
MaterialConcrete
DeckConcrete, precast panels
Main spans1
Design loadHS 20
Structure length30 ft (9.1 m)
Longest span29 ft (8.8 m)
Deck width21 ft (6.5 m)
Roadway width18 ft (5.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic148 (2020)
Projected traffic210 by 2040
Trucks15%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.8 mi (159 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$500,000 (2018 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Mary M Knight RD over Dry Creek built?

It was built in 1970, making it 55 years old in 2025.

What condition is Mary M Knight RD over Dry 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 2024.

How much traffic does Mary M Knight RD over Dry Creek carry?

About 148 vehicles per day (2020 count), of which roughly 15% are trucks.

How long is Mary M Knight RD over Dry Creek?

The structure is 30 ft (9.1 m) long with a longest span of 29 ft (8.8 m) and a deck 21 ft wide.

Who owns Mary M Knight RD over Dry Creek?

It is owned by the County Highway Agency.