US Bridges

S 89 over Local-Blacktail Cr-Rr

Fair

Beaverhead County, Montana · Dillon · Structure no. P00089002+06021

Built
1974
51 years old
Condition
Fair
inspected December 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
322 ft
5 main spans
Daily traffic
4,241
2023 count
Owner
State
State Highway Agency

About this bridge

S 89 over Local-Blacktail Cr-Rr is a prestressed concrete stringer/multi-beam or girder carrying S 89 over Local-Blacktail Cr-Rr in Beaverhead County, Montana. It was built in 1974, so it is 51 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 4,241 vehicles a day, roughly 5% of them trucks, projected to reach 4,453 by 2043. The structure is 322 ft (98.1 m) long and 47 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesS 89
CrossesLocal-Blacktail Cr-Rr
LocationDillon
RouteState Highway 89
CountyBeaverhead County
StateMontana
Coordinates45.22827, -112.63176
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionDecember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating44 US tons
Inventory rating24 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans5
Design loadHS 20
Structure length322 ft (98.1 m)
Longest span76 ft (23.3 m)
Deck width47 ft (14.2 m)
Roadway width44 ft (13.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,241 (2023)
Projected traffic4,453 by 2043
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway, waterway and railroad
Detour if closed5 mi (8 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was S 89 over Local-Blacktail Cr-Rr built?

It was built in 1974, making it 51 years old in 2025.

What condition is S 89 over Local-Blacktail Cr-Rr 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 December 2024.

How much traffic does S 89 over Local-Blacktail Cr-Rr carry?

About 4,241 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is S 89 over Local-Blacktail Cr-Rr?

The structure is 322 ft (98.1 m) long with a longest span of 76 ft (23.3 m) and a deck 47 ft wide.

Who owns S 89 over Local-Blacktail Cr-Rr?

It is owned by the State Highway Agency.