US Bridges

170 ST over Trib of Tarkio Rvr

GoodPosted for load

Atchison County, Missouri · S 33 T 66 N R 39 W · Structure no. 20671

Built
1950
75 years old, rebuilt 1986
Condition
Good
inspected February 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
24 ft
1 main span
Daily traffic
20
2024 count
Owner
County
County Highway Agency

About this bridge

170 ST over Trib of Tarkio Rvr is a steel stringer/multi-beam or girder carrying 170 ST over Trib of Tarkio Rvr in Atchison County, Missouri. It was built in 1950 and reconstructed in 1986, so it is 75 years old, older than the Missouri average of 45.1 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. Its operating status is: posted for load restriction.

It carries about 20 vehicles a day, roughly 10% of them trucks, projected to reach 23 by 2044. The structure is 24 ft (7.3 m) long and 21 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
Carries170 ST
CrossesTrib of Tarkio Rvr
LocationS 33 T 66 N R 39 W
RouteCounty Highway 270
CountyAtchison County
StateMissouri
Coordinates40.48052, -95.32974
Functional classRural Local

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionFebruary 2024
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour above top of footing
Structural evaluation3: Basically intolerable, requiring high priority of corrective action
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating24.8 US tons
Inventory rating9.9 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadOther
Structure length24 ft (7.3 m)
Longest span23 ft (7 m)
Deck width21 ft (6.3 m)
Roadway width20 ft (6.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic20 (2024)
Projected traffic23 by 2044
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 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 proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$174,000 (2025 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was 170 ST over Trib of Tarkio Rvr built?

It was built in 1950, making it 75 years old in 2025. It was reconstructed in 1986.

What condition is 170 ST over Trib of Tarkio Rvr in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in February 2024.

How much traffic does 170 ST over Trib of Tarkio Rvr carry?

About 20 vehicles per day (2024 count), of which roughly 10% are trucks.

How long is 170 ST over Trib of Tarkio Rvr?

The structure is 24 ft (7.3 m) long with a longest span of 23 ft (7 m) and a deck 21 ft wide.

Who owns 170 ST over Trib of Tarkio Rvr?

It is owned by the County Highway Agency.