US Bridges

Irr-Us 2 over Unstable Slope

Poor

Flathead County, Montana · 1.9M SE Essex · Structure no. 000000000007056

Built
1981
44 years old
Condition
Poor
inspected October 2023
Type
Other
Concrete
Length
260 ft
1 main span
Daily traffic
1,013
2023 count
Owner
State
State Highway Agency

About this bridge

Irr-Us 2 over Unstable Slope is a concrete other carrying Irr-Us 2 over Unstable Slope in Flathead County, Montana. It was built in 1981, so it is 44 years old, younger than the Montana average of 47 years.

The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

It carries about 1,013 vehicles a day, roughly 5% of them trucks, projected to reach 1,063 by 2043. The structure is 260 ft (79.2 m) long and 16 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesIrr-Us 2
CrossesUnstable Slope
Location1.9M SE Essex
RouteU.S. Route 1
CountyFlathead County
StateMontana
Coordinates48.26162, -113.57634
Functional classRural Principal Arterial - Other

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Last inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Approach roadway alignment8: Equal to present desirable criteria
Operating rating36 US tons
Inventory rating36 US tons

Structure

Structure typeOther
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHL 93
Structure length260 ft (79.2 m)
Longest span251 ft (76.6 m)
Deck width16 ft (4.9 m)
Roadway width15 ft (4.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,013 (2023)
Projected traffic1,063 by 2043
Trucks5%
Lanes on structure1
Traffic directionOne-way traffic
CarriesHighway
CrossesOther
Detour if closed123.7 mi (199 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkNon-Interstate 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 Irr-Us 2 over Unstable Slope built?

It was built in 1981, making it 44 years old in 2025.

What condition is Irr-Us 2 over Unstable Slope in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in October 2023.

How much traffic does Irr-Us 2 over Unstable Slope carry?

About 1,013 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is Irr-Us 2 over Unstable Slope?

The structure is 260 ft (79.2 m) long with a longest span of 251 ft (76.6 m) and a deck 16 ft wide.

Who owns Irr-Us 2 over Unstable Slope?

It is owned by the State Highway Agency.