US Bridges

IRR County Road 20 over Smoke Creek 016

Fair

Roosevelt County, Montana · 21M N Brockton · Structure no. L43205005+09001

Built
1955
70 years old
Condition
Fair
inspected July 2023
Type
Truss - Thru
Steel
Length
94 ft
1 main span
Daily traffic
100
2025 count
Owner
County
County Highway Agency

About this bridge

IRR County Road 20 over Smoke Creek 016 is a steel truss - thru carrying IRR County Road 20 over Smoke Creek 016 in Roosevelt County, Montana. It was built in 1955, so it is 70 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 100 vehicles a day, roughly 3% of them trucks, projected to reach 100 by 2040. The structure is 94 ft (28.7 m) long and 21 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

Location

Open in Google Maps
CarriesIRR County Road 20
CrossesSmoke Creek 016
Location21M N Brockton
RouteCounty Highway 43205
CountyRoosevelt County
StateMontana
Coordinates48.47628, -104.95167
Functional classRural Minor 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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating50 US tons
Inventory rating30 US tons

Structure

Structure typeTruss - Thru
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadUnknown
Structure length94 ft (28.7 m)
Longest span90 ft (27.4 m)
Deck width21 ft (6.5 m)
Roadway width19 ft (5.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic100 (2025)
Projected traffic100 by 2040
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.8 mi (11 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 IRR County Road 20 over Smoke Creek 016 built?

It was built in 1955, making it 70 years old in 2025.

What condition is IRR County Road 20 over Smoke Creek 016 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 July 2023.

How much traffic does IRR County Road 20 over Smoke Creek 016 carry?

About 100 vehicles per day (2025 count), of which roughly 3% are trucks.

How long is IRR County Road 20 over Smoke Creek 016?

The structure is 94 ft (28.7 m) long with a longest span of 90 ft (27.4 m) and a deck 21 ft wide.

Who owns IRR County Road 20 over Smoke Creek 016?

It is owned by the County Highway Agency.