US Bridges

MT-43 FH 20 over Trail Creek

Good

Beaverhead County, Montana · 17 M W Wisdom · Structure no. 000000202105862

Built
2021
4 years old
Condition
Good
inspected October 2023
Type
Slab
Prestressed Concrete
Length
73 ft
1 main span
Daily traffic
461
2023 count
Owner
State
State Highway Agency

About this bridge

MT-43 FH 20 over Trail Creek is a prestressed concrete slab carrying MT-43 FH 20 over Trail Creek in Beaverhead County, Montana. It was built in 2021, so it is 4 years old, younger than the Montana average of 47 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 461 vehicles a day, roughly 11% of them trucks, projected to reach 484 by 2043. The structure is 73 ft (22.1 m) long and 32 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

CarriesMT-43 FH 20
CrossesTrail Creek
Location17 M W Wisdom
RouteState Highway 46
StateMontana
Coordinates45.6543, -113.7844
Functional classRural Minor Arterial

Condition and inspection

Good

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

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Channel and channel protection7 GoodSome minor problems.
Last inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation8: Equal to present desirable criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating69 US tons
Inventory rating50 US tons

Structure

Structure typeSlab
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans1
Design loadHL 93
Structure length73 ft (22.1 m)
Longest span70 ft (21.3 m)
Deck width32 ft (9.8 m)
Roadway width29 ft (8.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic461 (2023)
Projected traffic484 by 2043
Trucks11%
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 statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was MT-43 FH 20 over Trail Creek built?

It was built in 2021, making it 4 years old in 2025.

What condition is MT-43 FH 20 over Trail Creek 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 October 2023.

How much traffic does MT-43 FH 20 over Trail Creek carry?

About 461 vehicles per day (2023 count), of which roughly 11% are trucks.

How long is MT-43 FH 20 over Trail Creek?

The structure is 73 ft (22.1 m) long with a longest span of 70 ft (21.3 m) and a deck 32 ft wide.

Who owns MT-43 FH 20 over Trail Creek?

It is owned by the State Highway Agency.