US Bridges

S 366-LEDGER RD over Dry Fork Marias River

FairPosted for load

Pondera County, Montana · Ledger · Structure no. S00366005+09001

Built
1952
73 years old
Condition
Fair
inspected October 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
107 ft
2 main spans
Daily traffic
169
2023 count
Owner
State
State Highway Agency

About this bridge

S 366-LEDGER RD over Dry Fork Marias River is a steel continuous stringer/multi-beam or girder carrying S 366-LEDGER RD over Dry Fork Marias River in Pondera County, Montana. It was built in 1952, so it is 73 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. Its operating status is: posted for load restriction.

It carries about 169 vehicles a day, roughly 5% of them trucks, projected to reach 177 by 2043. The structure is 107 ft (32.6 m) long and 27 ft wide. If it were closed, the detour would be 39.8 mi (64 km).

Location

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CarriesS 366-LEDGER RD
CrossesDry Fork Marias River
LocationLedger
RouteState Highway 366
CountyPondera County
StateMontana
Coordinates48.26033, -111.81952
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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusPosted for load 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 geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating37 US tons
Inventory rating22 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadH 15
Structure length107 ft (32.6 m)
Longest span53 ft (16.2 m)
Deck width27 ft (8.2 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic169 (2023)
Projected traffic177 by 2043
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed39.8 mi (64 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was S 366-LEDGER RD over Dry Fork Marias River built?

It was built in 1952, making it 73 years old in 2025.

What condition is S 366-LEDGER RD over Dry Fork Marias 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 October 2023.

How much traffic does S 366-LEDGER RD over Dry Fork Marias River carry?

About 169 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is S 366-LEDGER RD over Dry Fork Marias River?

The structure is 107 ft (32.6 m) long with a longest span of 53 ft (16.2 m) and a deck 27 ft wide.

Who owns S 366-LEDGER RD over Dry Fork Marias River?

It is owned by the State Highway Agency.