US Bridges

IRR - US 93 over Post Creek

Fair

Lake County, Montana · 6M N ST Ignatius · Structure no. P00005037+07681

Built
1933
92 years old, rebuilt 1955
Condition
Fair
inspected July 2023
Type
Tee Beam
Concrete
Length
51 ft
2 main spans
Daily traffic
8,158
2023 count
Owner
State
State Highway Agency

About this bridge

IRR - US 93 over Post Creek is a concrete tee beam carrying IRR - US 93 over Post Creek in Lake County, Montana. It was built in 1933 and reconstructed in 1955, so it is 92 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 8,158 vehicles a day, roughly 5% of them trucks, projected to reach 8,566 by 2043. The structure is 51 ft (15.5 m) long and 31 ft wide. If it were closed, the detour would be 36 mi (58 km).

Location

Open in Google Maps
CarriesIRR - US 93
CrossesPost Creek
Location6M N ST Ignatius
RouteU.S. Route 93
CountyLake County
StateMontana
Coordinates47.39533, -114.09671
Functional classRural Principal Arterial - Other

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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating49.1 US tons
Inventory rating30 US tons

Structure

Structure typeTee Beam
MaterialConcrete
DeckNot applicable
Main spans2
Design loadH 15
Structure length51 ft (15.5 m)
Longest span26 ft (7.9 m)
Deck width31 ft (9.4 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic8,158 (2023)
Projected traffic8,566 by 2043
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed36 mi (58 km)
TollOn a free road
National Highway SystemYes

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$140,000
NavigationNo navigation control on waterway

Frequently asked questions

When was IRR - US 93 over Post Creek built?

It was built in 1933, making it 92 years old in 2025. It was reconstructed in 1955.

What condition is IRR - US 93 over Post Creek 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 2023.

How much traffic does IRR - US 93 over Post Creek carry?

About 8,158 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is IRR - US 93 over Post Creek?

The structure is 51 ft (15.5 m) long with a longest span of 26 ft (7.9 m) and a deck 31 ft wide.

Who owns IRR - US 93 over Post Creek?

It is owned by the State Highway Agency.