US Bridges

US 89 over Big Muddy Creek

Good

Teton County, Montana · Bynum · Structure no. P00003055+06641

Built
2010
15 years old
Condition
Good
inspected March 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
313 ft
5 main spans
Daily traffic
609
2023 count
Owner
State
State Highway Agency

About this bridge

US 89 over Big Muddy Creek is a prestressed concrete stringer/multi-beam or girder carrying US 89 over Big Muddy Creek in Teton County, Montana. It was built in 2010, so it is 15 years old, younger than the Montana average of 47 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 609 vehicles a day, roughly 5% of them trucks, projected to reach 639 by 2043. The structure is 313 ft (95.3 m) long and 38 ft wide. If it were closed, the detour would be 24.9 mi (40 km).

CarriesUS 89
CrossesBig Muddy Creek
LocationBynum
RouteU.S. Route 89
StateMontana
Coordinates47.9843, -112.31522
Functional classRural Minor Arterial

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure8 Very GoodNo problems noted.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMarch 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation7: Better than present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating50 US tons
Inventory rating33 US tons

Structure

MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans5
Design loadHL 93
Structure length313 ft (95.3 m)
Longest span63 ft (19.1 m)
Deck width38 ft (11.7 m)
Roadway width36 ft (11 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic609 (2023)
Projected traffic639 by 2043
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed24.9 mi (40 km)
TollOn a free road
National Highway SystemNo

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 US 89 over Big Muddy Creek built?

It was built in 2010, making it 15 years old in 2025.

What condition is US 89 over Big Muddy Creek in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in March 2024.

How much traffic does US 89 over Big Muddy Creek carry?

About 609 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is US 89 over Big Muddy Creek?

The structure is 313 ft (95.3 m) long with a longest span of 63 ft (19.1 m) and a deck 38 ft wide.

Who owns US 89 over Big Muddy Creek?

It is owned by the State Highway Agency.