US Bridges

US 12 over Nine Mile Hill Road

Good

Walla Walla County, Washington · 10.3 E JCT US 730 Spur · Structure no. 0019406B0000000

Built
2023
2 years old
Condition
Good
inspected July 2023
Type
Slab
Prestressed Concrete
Length
56 ft
1 main span
Daily traffic
4,070
2023 count
Owner
State
State Highway Agency

About this bridge

US 12 over Nine Mile Hill Road is a prestressed concrete slab carrying US 12 over Nine Mile Hill Road in Walla Walla 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 4,070 vehicles a day, roughly 16% of them trucks, projected to reach 4,642 by 2039. The structure is 56 ft (17.2 m) long and 41 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesUS 12
CrossesNine Mile Hill Road
Location10.3 E JCT US 730 Spur
RouteU.S. Route 12
CountyWalla Walla County
StateWashington
Coordinates46.05473, -118.70761
Functional classRural Principal Arterial - Other

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 inspectionJuly 2023
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 rating89.9 US tons
Inventory rating62.2 US tons

Structure

Structure typeSlab
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHL 93
Structure length56 ft (17.2 m)
Longest span42 ft (12.8 m)
Deck width41 ft (12.5 m)
Roadway width38 ft (11.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,070 (2023)
Projected traffic4,642 by 2039
Trucks16%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes

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$1.1 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was US 12 over Nine Mile Hill Road built?

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

What condition is US 12 over Nine Mile Hill Road 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 US 12 over Nine Mile Hill Road carry?

About 4,070 vehicles per day (2023 count), of which roughly 16% are trucks.

How long is US 12 over Nine Mile Hill Road?

The structure is 56 ft (17.2 m) long with a longest span of 42 ft (12.8 m) and a deck 41 ft wide.

Who owns US 12 over Nine Mile Hill Road?

It is owned by the State Highway Agency.