US Bridges

IRR BIA RTE 73 over Rotten Grass Creek

Fair

Big Horn County, Montana · 7.6 KM SE of ST Xavier · Structure no. 00000000000C217

Built
1980
45 years old
Condition
Fair
inspected June 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
68 ft
1 main span
Daily traffic
200
2024 count
Owner
Federal
Bureau of Indian Affairs

About this bridge

IRR BIA RTE 73 over Rotten Grass Creek is a prestressed concrete stringer/multi-beam or girder carrying IRR BIA RTE 73 over Rotten Grass Creek in Big Horn County, Montana. It was built in 1980, so it is 45 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 200 vehicles a day, roughly 20% of them trucks, projected to reach 234 by 2044. The structure is 68 ft (20.6 m) long and 34 ft wide. If it were closed, the detour would be 55.3 mi (89 km).

CarriesIRR BIA RTE 73
CrossesRotten Grass Creek
Location7.6 KM SE of ST Xavier
RouteFederal Lands Road 73
StateMontana
Coordinates45.41206, -107.68308
Functional classRural Minor Arterial

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionJune 2024
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 adequacy7: Better than present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating55.4 US tons
Inventory rating33.1 US tons

Structure

MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length68 ft (20.6 m)
Longest span65 ft (19.8 m)
Deck width34 ft (10.4 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic200 (2024)
Projected traffic234 by 2044
Trucks20%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed55.3 mi (89 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerBureau of Indian Affairs
Maintained byBureau of Indian Affairs
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 IRR BIA RTE 73 over Rotten Grass Creek built?

It was built in 1980, making it 45 years old in 2025.

What condition is IRR BIA RTE 73 over Rotten Grass 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 June 2024.

How much traffic does IRR BIA RTE 73 over Rotten Grass Creek carry?

About 200 vehicles per day (2024 count), of which roughly 20% are trucks.

How long is IRR BIA RTE 73 over Rotten Grass Creek?

The structure is 68 ft (20.6 m) long with a longest span of 65 ft (19.8 m) and a deck 34 ft wide.

Who owns IRR BIA RTE 73 over Rotten Grass Creek?

It is owned by the Bureau of Indian Affairs.