US Bridges

S 556-THOMPSON R R over Thompson River

Fair

Sanders County, Montana · 26M NE Thompson Falls · Structure no. S00556020+09691

Built
1992
33 years old
Condition
Fair
inspected August 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
57 ft
1 main span
Daily traffic
3
2023 count
Owner
County
County Highway Agency

About this bridge

S 556-THOMPSON R R over Thompson River is a steel stringer/multi-beam or girder carrying S 556-THOMPSON R R over Thompson River in Sanders County, Montana. It was built in 1992, so it is 33 years old, younger than the Montana average of 47 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 3 vehicles a day, projected to reach 3 by 2043. The structure is 57 ft (17.3 m) long and 17 ft wide. If it were closed, the detour would be 29.8 mi (48 km).

Location

Open in Google Maps
CarriesS 556-THOMPSON R R
CrossesThompson River
Location26M NE Thompson Falls
RouteCounty Highway 556
CountySanders County
StateMontana
Coordinates47.77111, -114.98541
Functional classRural Major Collector

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, 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 evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating45.6 US tons
Inventory rating34.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans1
Design loadHS 20
Structure length57 ft (17.3 m)
Longest span54 ft (16.5 m)
Deck width17 ft (5.1 m)
Roadway width14 ft (4.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3 (2023)
Projected traffic3 by 2043
Trucks0%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed29.8 mi (48 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty 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 556-THOMPSON R R over Thompson River built?

It was built in 1992, making it 33 years old in 2025.

What condition is S 556-THOMPSON R R over Thompson River in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in August 2024.

How much traffic does S 556-THOMPSON R R over Thompson River carry?

About 3 vehicles per day (2023 count).

How long is S 556-THOMPSON R R over Thompson River?

The structure is 57 ft (17.3 m) long with a longest span of 54 ft (16.5 m) and a deck 17 ft wide.

Who owns S 556-THOMPSON R R over Thompson River?

It is owned by the County Highway Agency.