US Bridges

US 12 over Drainage

Poor

Rosebud County, Montana · 18M NW Forsyth · Structure no. P00014253+00221

Built
1938
87 years old
Condition
Poor
inspected August 2024
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
39 ft
2 main spans
Daily traffic
214
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 1938, so it is 87 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 214 vehicles a day, roughly 15% of them trucks, projected to reach 225 by 2043. The structure is 39 ft (11.9 m) long and 30 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesUS 12
CrossesDrainage
Location18M NW Forsyth
RouteU.S. Route 12
CountyRosebud County
StateMontana
Coordinates46.38478, -106.99283
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.
Superstructure7 GoodSome minor problems.
Substructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Channel and channel protection8 Very GoodNo problems noted.
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 geometry6: Equal to present minimum criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating47 US tons
Inventory rating32 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans2
Design loadH 15
Structure length39 ft (11.9 m)
Longest span19 ft (5.8 m)
Deck width30 ft (9.1 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic214 (2023)
Projected traffic225 by 2043
Trucks15%
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 proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$77,000
NavigationNo navigation control on waterway

Frequently asked questions

When was US 12 over Drainage built?

It was built in 1938, making it 87 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 214 vehicles per day (2023 count), of which roughly 15% are trucks.

How long is US 12 over Drainage?

The structure is 39 ft (11.9 m) long with a longest span of 19 ft (5.8 m) and a deck 30 ft wide.

Who owns US 12 over Drainage?

It is owned by the State Highway Agency.