US Bridges

S 5 over Main Creek

Poor

Sheridan County, Montana · 9M SW Westby · Structure no. P00030014+03181

Built
1939
86 years old
Condition
Poor
inspected August 2024
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
97 ft
5 main spans
Daily traffic
309
2023 count
Owner
State
State Highway Agency

About this bridge

S 5 over Main Creek is a wood or timber stringer/multi-beam or girder carrying S 5 over Main Creek in Sheridan County, Montana. It was built in 1939, so it is 86 years old, older than the Montana average of 47 years.

The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

It carries about 309 vehicles a day, roughly 26% of them trucks, projected to reach 324 by 2043. The structure is 97 ft (29.6 m) long and 26 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesS 5
CrossesMain Creek
Location9M SW Westby
RouteState Highway 5
CountySheridan County
StateMontana
Coordinates48.81711, -104.23653
Functional classRural Minor Arterial

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Substructure4 PoorAdvanced section loss, deterioration, spalling or scour.
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 evaluation4: Meets minimum tolerable limits to be 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 alignment8: Equal to present desirable criteria
Operating rating39 US tons
Inventory rating26 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans5
Design loadH 15
Structure length97 ft (29.6 m)
Longest span19 ft (5.8 m)
Deck width26 ft (7.9 m)
Roadway width24 ft (7.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic309 (2023)
Projected traffic324 by 2043
Trucks26%
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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was S 5 over Main Creek built?

It was built in 1939, making it 86 years old in 2025.

What condition is S 5 over Main Creek in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in August 2024.

How much traffic does S 5 over Main Creek carry?

About 309 vehicles per day (2023 count), of which roughly 26% are trucks.

How long is S 5 over Main Creek?

The structure is 97 ft (29.6 m) long with a longest span of 19 ft (5.8 m) and a deck 26 ft wide.

Who owns S 5 over Main Creek?

It is owned by the State Highway Agency.