US Bridges

I 15 over Int S Montana Street

Fair

Silver Bow County, Montana · Butte · Structure no. I00015126+03162

Built
1961
64 years old
Condition
Fair
inspected February 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
168 ft
1 main span
Daily traffic
9,878
2023 count
Owner
State
State Highway Agency

About this bridge

I 15 over Int S Montana Street is a steel stringer/multi-beam or girder carrying I 15 over Int S Montana Street in Silver Bow County, Montana. It was built in 1961, so it is 64 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 5 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 9,878 vehicles a day, roughly 11% of them trucks, projected to reach 10,569 by 2043. The structure is 168 ft (51.2 m) long and 32 ft wide.

Location

Open in Google Maps
CarriesI 15
CrossesInt S Montana Street
LocationButte
RouteInterstate 15
CountySilver Bow County
StateMontana
Coordinates45.99255, -112.53909
Functional classUrban 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.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionFebruary 2023
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 geometry2: Basically intolerable, requiring high priority of replacement
Approach roadway alignment7: Better than present minimum criteria
Operating rating46.1 US tons
Inventory rating35.7 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1 (+2 approach)
Design loadHS 20
Structure length168 ft (51.2 m)
Longest span75 ft (22.9 m)
Deck width32 ft (9.7 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic9,878 (2023)
Projected traffic10,569 by 2043
Trucks11%
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 statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$348,000
NavigationNot applicable (no waterway)

Frequently asked questions

When was I 15 over Int S Montana Street built?

It was built in 1961, making it 64 years old in 2025.

What condition is I 15 over Int S Montana Street 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 February 2023.

How much traffic does I 15 over Int S Montana Street carry?

About 9,878 vehicles per day (2023 count), of which roughly 11% are trucks.

How long is I 15 over Int S Montana Street?

The structure is 168 ft (51.2 m) long with a longest span of 75 ft (22.9 m) and a deck 32 ft wide.

Who owns I 15 over Int S Montana Street?

It is owned by the State Highway Agency.