US Bridges

US 12 over Drainage

Poor

Rosebud County, Montana · 31M NW Forsyth · Structure no. P00014239+08151

Built
1941
84 years old
Condition
Poor
inspected August 2024
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
57 ft
3 main spans
Daily traffic
222
2023 count
Owner
State
State Highway Agency

About this bridge

US 12 over Drainage is a wood or timber stringer/multi-beam or girder carrying US 12 over Drainage in Rosebud County, Montana. It was built in 1941, so it is 84 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 222 vehicles a day, roughly 14% of them trucks, projected to reach 233 by 2043. The structure is 57 ft (17.4 m) long and 26 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

CarriesUS 12
CrossesDrainage
Location31M NW Forsyth
RouteU.S. Route 12
StateMontana
Coordinates46.50728, -107.20258
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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
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 adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating42 US tons
Inventory rating27 US tons

Structure

MaterialWood or Timber
DeckWood or timber
Main spans3
Design loadH 15
Structure length57 ft (17.4 m)
Longest span19 ft (5.8 m)
Deck width26 ft (7.9 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic222 (2023)
Projected traffic233 by 2043
Trucks14%
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 US 12 over Drainage built?

It was built in 1941, making it 84 years old in 2025.

What condition is US 12 over Drainage 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 US 12 over Drainage carry?

About 222 vehicles per day (2023 count), of which roughly 14% are trucks.

How long is US 12 over Drainage?

The structure is 57 ft (17.4 m) long with a longest span of 19 ft (5.8 m) and a deck 26 ft wide.

Who owns US 12 over Drainage?

It is owned by the State Highway Agency.