US Bridges

Lone Mountain Trl over W Fork W Gallatin 001

Fair

Gallatin County, Montana · 2M E Big Sky · Structure no. L16064000+03081

Built
1972
53 years old
Condition
Fair
inspected July 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
103 ft
1 main span
Daily traffic
9,730
2023 count
Owner
State
State Highway Agency

About this bridge

Lone Mountain Trl over W Fork W Gallatin 001 is a prestressed concrete stringer/multi-beam or girder carrying Lone Mountain Trl over W Fork W Gallatin 001 in Gallatin County, Montana. It was built in 1972, so it is 53 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 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 9,730 vehicles a day, roughly 1% of them trucks, projected to reach 11,433 by 2043. The structure is 103 ft (31.4 m) long and 32 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesLone Mountain Trl
CrossesW Fork W Gallatin 001
Location2M E Big Sky
RouteState Highway 64
CountyGallatin County
StateMontana
Coordinates45.26574, -111.25716
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.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJuly 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 geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating75 US tons
Inventory rating41 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length103 ft (31.4 m)
Longest span100 ft (30.5 m)
Deck width32 ft (9.8 m)
Roadway width30 ft (9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic9,730 (2023)
Projected traffic11,433 by 2043
Trucks1%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed123.7 mi (199 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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$287,000
NavigationNo navigation control on waterway

Frequently asked questions

When was Lone Mountain Trl over W Fork W Gallatin 001 built?

It was built in 1972, making it 53 years old in 2025.

What condition is Lone Mountain Trl over W Fork W Gallatin 001 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 2024.

How much traffic does Lone Mountain Trl over W Fork W Gallatin 001 carry?

About 9,730 vehicles per day (2023 count), of which roughly 1% are trucks.

How long is Lone Mountain Trl over W Fork W Gallatin 001?

The structure is 103 ft (31.4 m) long with a longest span of 100 ft (30.5 m) and a deck 32 ft wide.

Who owns Lone Mountain Trl over W Fork W Gallatin 001?

It is owned by the State Highway Agency.