SR 99 over Mercer ST
GoodKing County, Washington · 5.7 N JCT SR 509 · Structure no. 0018549C0000000
- Built
- 2015
- 10 years old
- Condition
- Good
- inspected August 2023
- Type
- Stringer/Multi-beam or Girder
- Prestressed Concrete
- Length
- 129 ft
- 1 main span
- Daily traffic
- 12,045
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
SR 99 over Mercer ST is a prestressed concrete stringer/multi-beam or girder carrying SR 99 over Mercer ST in King County, Washington. It was built in 2015, so it is 10 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 12,045 vehicles a day, roughly 4% of them trucks, projected to reach 22,477 by 2039. The structure is 129 ft (39.3 m) long and 117 ft wide. If it were closed, the detour would be 1.2 mi (2 km).
Location
Open in Google MapsCondition and inspection
All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 8 Very Good | No problems noted. |
| Superstructure | 8 Very Good | No problems noted. |
| Substructure | 8 Very Good | No problems noted. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was SR 99 over Mercer ST built?
It was built in 2015, making it 10 years old in 2025.
What condition is SR 99 over Mercer ST 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 August 2023.
How much traffic does SR 99 over Mercer ST carry?
About 12,045 vehicles per day (2023 count), of which roughly 4% are trucks.
How long is SR 99 over Mercer ST?
The structure is 129 ft (39.3 m) long with a longest span of 124 ft (37.8 m) and a deck 117 ft wide.
Who owns SR 99 over Mercer ST?
It is owned by the State Highway Agency.