US Bridges

SR 20 over Twisp R

Good

Okanogan County, Washington · 38.8 E Chelan CO · Structure no. 0015714A0000000

Built
2000
25 years old
Condition
Good
inspected July 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
198 ft
1 main span
Daily traffic
4,361
2023 count
Owner
State
State Highway Agency

About this bridge

SR 20 over Twisp R is a prestressed concrete stringer/multi-beam or girder carrying SR 20 over Twisp R in Okanogan County, Washington. It was built in 2000, so it is 25 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 4,361 vehicles a day, roughly 9% of them trucks, projected to reach 5,315 by 2039. The structure is 198 ft (60.4 m) long and 45 ft wide. If it were closed, the detour would be 16.8 mi (27 km).

Location

Open in Google Maps
CarriesSR 20
CrossesTwisp R
Location38.8 E Chelan CO
RouteState Highway 20
CountyOkanogan County
StateWashington
Coordinates48.36717, -120.12247
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure8 Very GoodNo problems noted.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
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 rating96 US tons
Inventory rating48.9 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHL 93
Structure length198 ft (60.4 m)
Longest span191 ft (58.2 m)
Deck width45 ft (13.8 m)
Roadway width35 ft (10.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,361 (2023)
Projected traffic5,315 by 2039
Trucks9%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed16.8 mi (27 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$4.2 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 20 over Twisp R built?

It was built in 2000, making it 25 years old in 2025.

What condition is SR 20 over Twisp R 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 Twisp R carry?

About 4,361 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is SR 20 over Twisp R?

The structure is 198 ft (60.4 m) long with a longest span of 191 ft (58.2 m) and a deck 45 ft wide.

Who owns SR 20 over Twisp R?

It is owned by the State Highway Agency.