US Bridges

Benson Road over I-405

Good

King County, Washington · 0.1 N JCT SR 515 · Structure no. 0017624A0000000

Built
2010
15 years old
Condition
Good
inspected April 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
520 ft
3 main spans
Daily traffic
9,777
2010 count
Owner
State
State Highway Agency

About this bridge

Benson Road over I-405 is a prestressed concrete continuous stringer/multi-beam or girder carrying Benson Road over I-405 in King County, Washington. It was built in 2010, so it is 15 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 9,777 vehicles a day, roughly 8% of them trucks, projected to reach 15,780 by 2032. The structure is 520 ft (158.5 m) long and 43 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesBenson Road
CrossesI-405
Location0.1 N JCT SR 515
RouteCity Street 0
CountyKing County
StateWashington
Coordinates47.47031, -122.20639
Functional classUrban 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.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Last inspectionApril 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation8: Equal to present desirable criteria
Deck geometry7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating98 US tons
Inventory rating55 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHL 93
Structure length520 ft (158.5 m)
Longest span207 ft (63.1 m)
Deck width43 ft (13.1 m)
Roadway width34 ft (10.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic9,777 (2010)
Projected traffic15,780 by 2032
Trucks8%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesHighway
Detour if closed1.9 mi (3 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$12.6 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was Benson Road over I-405 built?

It was built in 2010, making it 15 years old in 2025.

What condition is Benson Road over I-405 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 April 2024.

How much traffic does Benson Road over I-405 carry?

About 9,777 vehicles per day (2010 count), of which roughly 8% are trucks.

How long is Benson Road over I-405?

The structure is 520 ft (158.5 m) long with a longest span of 207 ft (63.1 m) and a deck 43 ft wide.

Who owns Benson Road over I-405?

It is owned by the State Highway Agency.