US Bridges

I 15 over Highland Road

Fair

Silver Bow County, Montana · 7.4M N Divide · Structure no. I00015109+09511

Built
1976
49 years old
Condition
Fair
inspected August 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
76 ft
1 main span
Daily traffic
2,283
2023 count
Owner
State
State Highway Agency

About this bridge

I 15 over Highland Road is a prestressed concrete stringer/multi-beam or girder carrying I 15 over Highland Road in Silver Bow County, Montana. It was built in 1976, so it is 49 years old, older than the Montana average of 47 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 2,283 vehicles a day, roughly 20% of them trucks, projected to reach 2,465 by 2043. The structure is 76 ft (23.2 m) long and 44 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI 15
CrossesHighland Road
Location7.4M N Divide
RouteInterstate 15
CountySilver Bow County
StateMontana
Coordinates45.85279, -112.67538
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 inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating46 US tons
Inventory rating22 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length76 ft (23.2 m)
Longest span75 ft (22.9 m)
Deck width44 ft (13.4 m)
Roadway width41 ft (12.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,283 (2023)
Projected traffic2,465 by 2043
Trucks20%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was I 15 over Highland Road built?

It was built in 1976, making it 49 years old in 2025.

What condition is I 15 over Highland Road 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 August 2024.

How much traffic does I 15 over Highland Road carry?

About 2,283 vehicles per day (2023 count), of which roughly 20% are trucks.

How long is I 15 over Highland Road?

The structure is 76 ft (23.2 m) long with a longest span of 75 ft (22.9 m) and a deck 44 ft wide.

Who owns I 15 over Highland Road?

It is owned by the State Highway Agency.