US Bridges

MORTIMORE/3620 over Thorn Creek

Good

Whitman County, Washington · 1.44 MI SW Stoneham · Structure no. 081508000000000

Built
1977
48 years old
Condition
Good
inspected December 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
40 ft
1 main span
Daily traffic
16
2021 count
Owner
County
County Highway Agency

About this bridge

MORTIMORE/3620 over Thorn Creek is a prestressed concrete stringer/multi-beam or girder carrying MORTIMORE/3620 over Thorn Creek in Whitman County, Washington. It was built in 1977, so it is 48 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 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 16 vehicles a day, roughly 25% of them trucks, projected to reach 17 by 2044. The structure is 40 ft (12.2 m) long and 24 ft wide. If it were closed, the detour would be 14.9 mi (24 km).

Location

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CarriesMORTIMORE/3620
CrossesThorn Creek
Location1.44 MI SW Stoneham
RouteCounty Highway 36200
CountyWhitman County
StateWashington
Coordinates47.151, -117.46113
Functional classRural Local

Condition and inspection

Good

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

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionDecember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating35.4 US tons
Inventory rating16.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckOther
Main spans1
Design loadHS 20
Structure length40 ft (12.2 m)
Longest span38 ft (11.7 m)
Deck width24 ft (7.3 m)
Roadway width24 ft (7.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic16 (2021)
Projected traffic17 by 2044
Trucks25%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed14.9 mi (24 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$1.8 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was MORTIMORE/3620 over Thorn Creek built?

It was built in 1977, making it 48 years old in 2025.

What condition is MORTIMORE/3620 over Thorn 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 December 2023.

How much traffic does MORTIMORE/3620 over Thorn Creek carry?

About 16 vehicles per day (2021 count), of which roughly 25% are trucks.

How long is MORTIMORE/3620 over Thorn Creek?

The structure is 40 ft (12.2 m) long with a longest span of 38 ft (11.7 m) and a deck 24 ft wide.

Who owns MORTIMORE/3620 over Thorn Creek?

It is owned by the County Highway Agency.