US Bridges

Delphi Road over Dempsey Creek

Good

Thurston County, Washington · 2. SW Black Lake · Structure no. 086102000000000

Built
1995
30 years old
Condition
Good
inspected May 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
24 ft
1 main span
Daily traffic
4,432
2021 count
Owner
County
County Highway Agency

About this bridge

Delphi Road over Dempsey Creek is a wood or timber stringer/multi-beam or girder carrying Delphi Road over Dempsey Creek in Thurston County, Washington. It was built in 1995, so it is 30 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 4,432 vehicles a day, roughly 15% of them trucks, projected to reach 6,851 by 2041. The structure is 24 ft (7.3 m) long and 35 ft wide. If it were closed, the detour would be 16.2 mi (26 km).

Location

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CarriesDelphi Road
CrossesDempsey Creek
Location2. SW Black Lake
RouteCounty Highway 11155
CountyThurston County
StateWashington
Coordinates46.96482, -123.02101
Functional classRural Major Collector

Condition and inspection

Good

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

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation8: Equal to present desirable criteria
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 rating47.5 US tons
Inventory rating36.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadHS 20
Structure length24 ft (7.3 m)
Longest span22 ft (6.7 m)
Deck width35 ft (10.8 m)
Roadway width35 ft (10.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,432 (2021)
Projected traffic6,851 by 2041
Trucks15%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed16.2 mi (26 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 proposedDeck rehabilitation with only incidental widening
Estimated improvement cost$433,000 (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Delphi Road over Dempsey Creek built?

It was built in 1995, making it 30 years old in 2025.

What condition is Delphi Road over Dempsey 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 May 2023.

How much traffic does Delphi Road over Dempsey Creek carry?

About 4,432 vehicles per day (2021 count), of which roughly 15% are trucks.

How long is Delphi Road over Dempsey Creek?

The structure is 24 ft (7.3 m) long with a longest span of 22 ft (6.7 m) and a deck 35 ft wide.

Who owns Delphi Road over Dempsey Creek?

It is owned by the County Highway Agency.