US Bridges

Main ST over I-405

Good

King County, Washington · 2.2 N JCT I-90 · Structure no. 0019242N0000000

Built
2023
2 years old
Condition
Good
inspected June 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
290 ft
2 main spans
Daily traffic
3,519
2022 count
Owner
State
State Highway Agency

About this bridge

Main ST over I-405 is a prestressed concrete continuous stringer/multi-beam or girder carrying Main ST over I-405 in King County, Washington. It was built in 2023, so it is 2 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 3,519 vehicles a day, roughly 6% of them trucks, projected to reach 4,200 by 2042. The structure is 290 ft (88.4 m) long and 77 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesMain ST
CrossesI-405
Location2.2 N JCT I-90
RouteCity Street 405
CountyKing County
StateWashington
Coordinates47.61004, -122.1891
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 inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation8: Equal to present desirable criteria
Deck geometry2: Basically intolerable, requiring high priority of replacement
Approach roadway alignment8: Equal to present desirable criteria
Operating rating48.2 US tons
Inventory rating37.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHL 93
Structure length290 ft (88.4 m)
Longest span144 ft (43.9 m)
Deck width77 ft (23.4 m)
Roadway width49 ft (14.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,519 (2022)
Projected traffic4,200 by 2042
Trucks6%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesHighway
Detour if closed1.2 mi (2 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$7 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was Main ST over I-405 built?

It was built in 2023, making it 2 years old in 2025.

What condition is Main ST 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 June 2023.

How much traffic does Main ST over I-405 carry?

About 3,519 vehicles per day (2022 count), of which roughly 6% are trucks.

How long is Main ST over I-405?

The structure is 290 ft (88.4 m) long with a longest span of 144 ft (43.9 m) and a deck 77 ft wide.

Who owns Main ST over I-405?

It is owned by the State Highway Agency.