US Bridges

Old HWY 10 E over RR 046

Fair

Prairie County, Montana · 1M W Fallon · Structure no. L40004021+04001

Built
1934
91 years old, rebuilt 1949
Condition
Fair
inspected May 2023
Type
Tee Beam
Concrete
Length
148 ft
3 main spans
Daily traffic
507
2023 count
Owner
State
State Highway Agency

About this bridge

Old HWY 10 E over RR 046 is a concrete tee beam carrying Old HWY 10 E over RR 046 in Prairie County, Montana. It was built in 1934 and reconstructed in 1949, so it is 91 years old, older 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 6 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 507 vehicles a day, roughly 3% of them trucks, projected to reach 540 by 2043. The structure is 148 ft (45 m) long and 34 ft wide. If it were closed, the detour would be 16.2 mi (26 km).

Location

Open in Google Maps
CarriesOld HWY 10 E
CrossesRR 046
Location1M W Fallon
RouteState Highway 81020
CountyPrairie County
StateMontana
Coordinates46.83201, -105.13854
Functional classRural Local

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment6: Equal to present minimum criteria
Operating rating56 US tons
Inventory rating19 US tons

Structure

Structure typeTee Beam
MaterialConcrete
DeckConcrete, cast-in-place
Main spans3
Design loadH 15
Structure length148 ft (45 m)
Longest span51 ft (15.5 m)
Deck width34 ft (10.5 m)
Roadway width28 ft (8.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic507 (2023)
Projected traffic540 by 2043
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesRailroad
Detour if closed16.2 mi (26 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 proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$323,000
NavigationNot applicable (no waterway)

Frequently asked questions

When was Old HWY 10 E over RR 046 built?

It was built in 1934, making it 91 years old in 2025. It was reconstructed in 1949.

What condition is Old HWY 10 E over RR 046 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 May 2023.

How much traffic does Old HWY 10 E over RR 046 carry?

About 507 vehicles per day (2023 count), of which roughly 3% are trucks.

How long is Old HWY 10 E over RR 046?

The structure is 148 ft (45 m) long with a longest span of 51 ft (15.5 m) and a deck 34 ft wide.

Who owns Old HWY 10 E over RR 046?

It is owned by the State Highway Agency.