US Bridges

S 23 over Yellowstone River

Poor

Richland County, Montana · 2M S Sidney · Structure no. P00026001+02341

Built
1994
31 years old
Condition
Poor
inspected May 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
1,102 ft
5 main spans
Daily traffic
2,438
2023 count
Owner
State
State Highway Agency

About this bridge

S 23 over Yellowstone River is a steel continuous stringer/multi-beam or girder carrying S 23 over Yellowstone River in Richland County, Montana. It was built in 1994, so it is 31 years old, younger 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 2,438 vehicles a day, roughly 7% of them trucks, projected to reach 2,682 by 2043. The structure is 1,102 ft (335.9 m) long and 42 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

CarriesS 23
CrossesYellowstone River
Location2M S Sidney
RouteState Highway 23
StateMontana
Coordinates47.67401, -104.15868
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionMay 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating61 US tons
Inventory rating47 US tons

Structure

MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans5
Design loadHS 20
Structure length1,102 ft (335.9 m)
Longest span240 ft (73.2 m)
Deck width42 ft (12.9 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,438 (2023)
Projected traffic2,682 by 2043
Trucks7%
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 23 over Yellowstone River built?

It was built in 1994, making it 31 years old in 2025.

What condition is S 23 over Yellowstone 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 May 2024.

How much traffic does S 23 over Yellowstone River carry?

About 2,438 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is S 23 over Yellowstone River?

The structure is 1,102 ft (335.9 m) long with a longest span of 240 ft (73.2 m) and a deck 42 ft wide.

Who owns S 23 over Yellowstone River?

It is owned by the State Highway Agency.