US Bridges

RD 600 over Seventeen Mile CR

Fair

Lincoln County, Montana · Seventeen Mile · Structure no. 011405000000109

Built
1968
57 years old
Condition
Fair
inspected August 2024
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
29 ft
1 main span
Daily traffic
40
Owner
Federal
U.S. Forest Service

About this bridge

RD 600 over Seventeen Mile CR is a wood or timber stringer/multi-beam or girder carrying RD 600 over Seventeen Mile CR in Lincoln County, Montana. It was built in 1968, so it is 57 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 40 vehicles a day, projected to reach 60 by 2045. The structure is 29 ft (8.7 m) long and 15 ft wide. If it were closed, the detour would be 98.2 mi (158 km).

Location

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CarriesRD 600
CrossesSeventeen Mile CR
LocationSeventeen Mile
RouteFederal Lands Road 600
CountyLincoln County
StateMontana
Coordinates48.60307, -115.69503
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 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 geometry6: Equal to present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating56.4 US tons
Inventory rating43.5 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadHS 25 or greater
Structure length29 ft (8.7 m)
Longest span27 ft (8.2 m)
Deck width15 ft (4.7 m)
Roadway width14 ft (4.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic40 (—)
Projected traffic60 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 RD 600 over Seventeen Mile CR built?

It was built in 1968, making it 57 years old in 2025.

What condition is RD 600 over Seventeen Mile CR 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 August 2024.

How much traffic does RD 600 over Seventeen Mile CR carry?

About 40 vehicles per day (latest count).

How long is RD 600 over Seventeen Mile CR?

The structure is 29 ft (8.7 m) long with a longest span of 27 ft (8.2 m) and a deck 15 ft wide.

Who owns RD 600 over Seventeen Mile CR?

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