US Bridges

IRR - S 358 over Two Medicine River

Poor

Pondera County, Montana · 12M S Cut Bank · Structure no. S00358016+08321

Built
1968
57 years old
Condition
Poor
inspected August 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
318 ft
5 main spans
Daily traffic
243
2023 count
Owner
State
State Highway Agency

About this bridge

IRR - S 358 over Two Medicine River is a prestressed concrete stringer/multi-beam or girder carrying IRR - S 358 over Two Medicine River in Pondera 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 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 243 vehicles a day, roughly 9% of them trucks, projected to reach 255 by 2043. The structure is 318 ft (96.9 m) long and 36 ft wide. If it were closed, the detour would be 31.1 mi (50 km).

Location

Open in Google Maps
CarriesIRR - S 358
CrossesTwo Medicine River
Location12M S Cut Bank
RouteState Highway 358
CountyPondera County
StateMontana
Coordinates48.47221, -112.3584
Functional classRural Major Collector

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
Deck4 PoorAdvanced section loss, deterioration, spalling or scour.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 2023
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 adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating47 US tons
Inventory rating25 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans5
Design loadHS 15
Structure length318 ft (96.9 m)
Longest span65 ft (19.8 m)
Deck width36 ft (10.9 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic243 (2023)
Projected traffic255 by 2043
Trucks9%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed31.1 mi (50 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 IRR - S 358 over Two Medicine River built?

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

What condition is IRR - S 358 over Two Medicine River 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 2023.

How much traffic does IRR - S 358 over Two Medicine River carry?

About 243 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is IRR - S 358 over Two Medicine River?

The structure is 318 ft (96.9 m) long with a longest span of 65 ft (19.8 m) and a deck 36 ft wide.

Who owns IRR - S 358 over Two Medicine River?

It is owned by the State Highway Agency.