US Bridges

I 15 over Rr-Hwy 91-DRAINAGE

Fair

Madison County, Montana · 6.8M S Melrose · Structure no. I00015086+03272

Built
1974
51 years old, rebuilt 1996
Condition
Fair
inspected April 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
538 ft
4 main spans
Daily traffic
1,926
2023 count
Owner
State
State Highway Agency

About this bridge

I 15 over Rr-Hwy 91-DRAINAGE is a steel stringer/multi-beam or girder carrying I 15 over Rr-Hwy 91-DRAINAGE in Madison County, Montana. It was built in 1974 and reconstructed in 1996, so it is 51 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 1,926 vehicles a day, roughly 24% of them trucks, projected to reach 2,080 by 2043. The structure is 538 ft (164 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
CrossesRr-Hwy 91-DRAINAGE
Location6.8M S Melrose
RouteInterstate 15
CountyMadison County
StateMontana
Coordinates45.53937, -112.69731
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.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating49.1 US tons
Inventory rating36 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans4 (+3 approach)
Design loadHS 20
Structure length538 ft (164 m)
Longest span95 ft (29 m)
Deck width44 ft (13.4 m)
Roadway width41 ft (12.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,926 (2023)
Projected traffic2,080 by 2043
Trucks24%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway, waterway and railroad
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—
NavigationNo navigation control on waterway

Frequently asked questions

When was I 15 over Rr-Hwy 91-DRAINAGE built?

It was built in 1974, making it 51 years old in 2025. It was reconstructed in 1996.

What condition is I 15 over Rr-Hwy 91-DRAINAGE 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 April 2023.

How much traffic does I 15 over Rr-Hwy 91-DRAINAGE carry?

About 1,926 vehicles per day (2023 count), of which roughly 24% are trucks.

How long is I 15 over Rr-Hwy 91-DRAINAGE?

The structure is 538 ft (164 m) long with a longest span of 95 ft (29 m) and a deck 44 ft wide.

Who owns I 15 over Rr-Hwy 91-DRAINAGE?

It is owned by the State Highway Agency.