US Bridges

I 15 over Sep Boulder Ave-Rr

Fair

Lewis and Clark County, Montana · Helena · Structure no. 000000000001178

Built
2016
9 years old
Condition
Fair
inspected July 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
791 ft
4 main spans
Daily traffic
14,810
2023 count
Owner
State
State Highway Agency

About this bridge

I 15 over Sep Boulder Ave-Rr is a steel continuous stringer/multi-beam or girder carrying I 15 over Sep Boulder Ave-Rr in Lewis and Clark County, Montana. It was built in 2016, so it is 9 years old, younger 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 14,810 vehicles a day, roughly 4% of them trucks, projected to reach 16,957 by 2043. The structure is 791 ft (241.1 m) long and 64 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI 15
CrossesSep Boulder Ave-Rr
LocationHelena
RouteInterstate 15
CountyLewis and Clark County
StateMontana
Coordinates46.59856, -112.00315
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.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating42 US tons
Inventory rating32 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHL 93
Structure length791 ft (241.1 m)
Longest span212 ft (64.6 m)
Deck width64 ft (19.5 m)
Roadway width61 ft (18.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic14,810 (2023)
Projected traffic16,957 by 2043
Trucks4%
Lanes on structure3
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway 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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$2.3 million
NavigationNot applicable (no waterway)

Frequently asked questions

When was I 15 over Sep Boulder Ave-Rr built?

It was built in 2016, making it 9 years old in 2025.

What condition is I 15 over Sep Boulder Ave-Rr 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 July 2024.

How much traffic does I 15 over Sep Boulder Ave-Rr carry?

About 14,810 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is I 15 over Sep Boulder Ave-Rr?

The structure is 791 ft (241.1 m) long with a longest span of 212 ft (64.6 m) and a deck 64 ft wide.

Who owns I 15 over Sep Boulder Ave-Rr?

It is owned by the State Highway Agency.