US Bridges

Porcupine CR Road over Gallatin River

Fair

Gallatin County, Montana · Gallatin Canyon · Structure no. 011106000000109

Built
1951
74 years old, rebuilt 2008
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Concrete
Length
134 ft
4 main spans
Daily traffic
99
Owner
Federal
U.S. Forest Service

About this bridge

Porcupine CR Road over Gallatin River is a concrete stringer/multi-beam or girder carrying Porcupine CR Road over Gallatin River in Gallatin County, Montana. It was built in 1951 and reconstructed in 2008, so it is 74 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 99 vehicles a day, projected to reach 148 by 2045. The structure is 134 ft (40.8 m) long and 18 ft wide. If it were closed, the detour would be 98.2 mi (158 km).

Location

Open in Google Maps
CarriesPorcupine CR Road
CrossesGallatin River
LocationGallatin Canyon
RouteFederal Lands Road 653
CountyGallatin County
StateMontana
Coordinates45.2259, -111.24942
Functional classRural Local

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating25.4 US tons
Inventory rating19.6 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialConcrete
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length134 ft (40.8 m)
Longest span50 ft (15.2 m)
Deck width18 ft (5.4 m)
Roadway width14 ft (4.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic99 (—)
Projected traffic148 by 2045
Trucks—
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.2 mi (158 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerU.S. Forest Service
Maintained byU.S. Forest Service
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Porcupine CR Road over Gallatin River built?

It was built in 1951, making it 74 years old in 2025. It was reconstructed in 2008.

What condition is Porcupine CR Road over Gallatin River 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 Porcupine CR Road over Gallatin River carry?

About 99 vehicles per day (latest count).

How long is Porcupine CR Road over Gallatin River?

The structure is 134 ft (40.8 m) long with a longest span of 50 ft (15.2 m) and a deck 18 ft wide.

Who owns Porcupine CR Road over Gallatin River?

It is owned by the U.S. Forest Service.