US Bridges

S 484 FH 51 over Otter Creek

Fair

Powder River County, Montana · 27M SE Ashland · Structure no. S00484023+02001

Built
1999
26 years old
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
123 ft
1 main span
Daily traffic
35
2023 count
Owner
County
County Highway Agency

About this bridge

S 484 FH 51 over Otter Creek is a prestressed concrete stringer/multi-beam or girder carrying S 484 FH 51 over Otter Creek in Powder River County, Montana. It was built in 1999, so it is 26 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 35 vehicles a day, roughly 6% of them trucks, projected to reach 37 by 2043. The structure is 123 ft (37.6 m) long and 30 ft wide. If it were closed, the detour would be 29.8 mi (48 km).

CarriesS 484 FH 51
CrossesOtter Creek
Location27M SE Ashland
RouteCounty Highway 484
StateMontana
Coordinates45.24933, -106.16189
Functional classRural Major Collector

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.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionSeptember 2023
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 rating53 US tons
Inventory rating33 US tons

Structure

MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length123 ft (37.6 m)
Longest span122 ft (37.2 m)
Deck width30 ft (9.2 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic35 (2023)
Projected traffic37 by 2043
Trucks6%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed29.8 mi (48 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty 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 S 484 FH 51 over Otter Creek built?

It was built in 1999, making it 26 years old in 2025.

What condition is S 484 FH 51 over Otter 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 September 2023.

How much traffic does S 484 FH 51 over Otter Creek carry?

About 35 vehicles per day (2023 count), of which roughly 6% are trucks.

How long is S 484 FH 51 over Otter Creek?

The structure is 123 ft (37.6 m) long with a longest span of 122 ft (37.2 m) and a deck 30 ft wide.

Who owns S 484 FH 51 over Otter Creek?

It is owned by the County Highway Agency.