US Bridges

I 15 Nbl over Spencer Road Ic

Fair

Clark County, Idaho · In Spencer · Structure no. 000000000011945

Built
1969
56 years old
Condition
Fair
inspected June 2023
Type
Stringer/Multi-beam or Girder
Concrete
Length
114 ft
3 main spans
Daily traffic
1,850
2023 count
Owner
State
State Highway Agency

About this bridge

I 15 Nbl over Spencer Road Ic is a concrete stringer/multi-beam or girder carrying I 15 Nbl over Spencer Road Ic in Clark County, Idaho. It was built in 1969, so it is 56 years old, older than the Idaho average of 45.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 1,850 vehicles a day, roughly 41% of them trucks, projected to reach 2,775 by 2042. The structure is 114 ft (34.7 m) long and 41 ft wide.

Location

Open in Google Maps
CarriesI 15 Nbl
CrossesSpencer Road Ic
LocationIn Spencer
RouteInterstate 15
CountyClark County
StateIdaho
Coordinates44.35706, -112.18642
Functional classRural Principal Arterial - Interstate

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJune 2023
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating69 US tons
Inventory rating41 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialConcrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length114 ft (34.7 m)
Longest span37 ft (11.3 m)
Deck width41 ft (12.4 m)
Roadway width38 ft (11.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,850 (2023)
Projected traffic2,775 by 2042
Trucks41%
Lanes on structure2
Traffic directionOne-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
Detour if closed—
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was I 15 Nbl over Spencer Road Ic built?

It was built in 1969, making it 56 years old in 2025.

What condition is I 15 Nbl over Spencer Road Ic in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in June 2023.

How much traffic does I 15 Nbl over Spencer Road Ic carry?

About 1,850 vehicles per day (2023 count), of which roughly 41% are trucks.

How long is I 15 Nbl over Spencer Road Ic?

The structure is 114 ft (34.7 m) long with a longest span of 37 ft (11.3 m) and a deck 41 ft wide.

Who owns I 15 Nbl over Spencer Road Ic?

It is owned by the State Highway Agency.