US Bridges

Lower N Fork RD over Swamp Creek 070

Fair

Beaverhead County, Montana · 3M N Wisdom · Structure no. L01003002+05001

Built
1975
50 years old
Condition
Fair
inspected October 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
32 ft
1 main span
Daily traffic
35
2023 count
Owner
County
County Highway Agency

About this bridge

Lower N Fork RD over Swamp Creek 070 is a steel stringer/multi-beam or girder carrying Lower N Fork RD over Swamp Creek 070 in Beaverhead County, Montana. It was built in 1975, so it is 50 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 35 vehicles a day, roughly 3% of them trucks, projected to reach 37 by 2043. The structure is 32 ft (9.8 m) long and 20 ft wide. If it were closed, the detour would be 11.8 mi (19 km).

Location

Open in Google Maps
CarriesLower N Fork RD
CrossesSwamp Creek 070
Location3M N Wisdom
RouteCounty Highway 1003
CountyBeaverhead County
StateMontana
Coordinates45.65909, -113.46991
Functional classRural Minor 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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
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 inspectionOctober 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 geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating55 US tons
Inventory rating33 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans1
Design loadUnknown
Structure length32 ft (9.8 m)
Longest span30 ft (9.1 m)
Deck width20 ft (6.2 m)
Roadway width16 ft (5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic35 (2023)
Projected traffic37 by 2043
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed11.8 mi (19 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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$57,000
NavigationNo navigation control on waterway

Frequently asked questions

When was Lower N Fork RD over Swamp Creek 070 built?

It was built in 1975, making it 50 years old in 2025.

What condition is Lower N Fork RD over Swamp Creek 070 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 October 2024.

How much traffic does Lower N Fork RD over Swamp Creek 070 carry?

About 35 vehicles per day (2023 count), of which roughly 3% are trucks.

How long is Lower N Fork RD over Swamp Creek 070?

The structure is 32 ft (9.8 m) long with a longest span of 30 ft (9.1 m) and a deck 20 ft wide.

Who owns Lower N Fork RD over Swamp Creek 070?

It is owned by the County Highway Agency.