US Bridges

SR 20 over Bonaparte Creek

Good

Okanogan County, Washington · 7.7 E JCT US 97 · Structure no. 0015877B0000000

Built
2001
24 years old
Condition
Good
inspected July 2023
Type
Slab
Prestressed Concrete
Length
56 ft
1 main span
Daily traffic
1,358
2023 count
Owner
State
State Highway Agency

About this bridge

SR 20 over Bonaparte Creek is a prestressed concrete slab carrying SR 20 over Bonaparte Creek in Okanogan County, Washington. It was built in 2001, so it is 24 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 1,358 vehicles a day, roughly 17% of them trucks, projected to reach 1,548 by 2039. The structure is 56 ft (17 m) long and 36 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesSR 20
CrossesBonaparte Creek
Location7.7 E JCT US 97
RouteState Highway 20
CountyOkanogan County
StateWashington
Coordinates48.65357, -119.29947
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
Deck8 Very GoodNo problems noted.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJuly 2023
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum 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 alignment8: Equal to present desirable criteria
Operating rating54.7 US tons
Inventory rating42.1 US tons

Structure

Structure typeSlab
MaterialPrestressed Concrete
DeckOther
Main spans1
Design loadHS 25 or greater
Structure length56 ft (17 m)
Longest span52 ft (15.8 m)
Deck width36 ft (11.1 m)
Roadway width33 ft (10.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,358 (2023)
Projected traffic1,548 by 2039
Trucks17%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.8 mi (159 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$848,000 (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 20 over Bonaparte Creek built?

It was built in 2001, making it 24 years old in 2025.

What condition is SR 20 over Bonaparte 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 July 2023.

How much traffic does SR 20 over Bonaparte Creek carry?

About 1,358 vehicles per day (2023 count), of which roughly 17% are trucks.

How long is SR 20 over Bonaparte Creek?

The structure is 56 ft (17 m) long with a longest span of 52 ft (15.8 m) and a deck 36 ft wide.

Who owns SR 20 over Bonaparte Creek?

It is owned by the State Highway Agency.