US Bridges

Main Boulder Road over Boulder River

FairClosed to traffic

Park County, Montana · 40M South of Springdale · Structure no. 000000202208056

Built
1940
85 years old
Condition
Fair
inspected September 2024
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
35 ft
1 main span
Daily traffic
157
2023 count
Owner
County
County Highway Agency

About this bridge

Main Boulder Road over Boulder River is a wood or timber stringer/multi-beam or girder carrying Main Boulder Road over Boulder River in Park County, Montana. It was built in 1940, so it is 85 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 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. Its operating status is: closed to all traffic.

It carries about 157 vehicles a day, roughly 17% of them trucks, projected to reach 165 by 2043. The structure is 35 ft (10.7 m) long and 15 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesMain Boulder Road
CrossesBoulder River
Location40M South of Springdale
RouteCounty Highway 34210
CountyPark County
StateMontana
Coordinates45.22661, -110.26007
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.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusClosed to all traffic
ScourScour evaluation has not been made
Structural evaluation*: *
Deck geometry0: Immediate repair necessary to put back in service
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating—
Inventory rating—

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadUnknown
Structure length35 ft (10.7 m)
Longest span32 ft (9.8 m)
Deck width15 ft (4.7 m)
Roadway width14 ft (4.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic157 (2023)
Projected traffic165 by 2043
Trucks17%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed123.7 mi (199 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 Main Boulder Road over Boulder River built?

It was built in 1940, making it 85 years old in 2025.

What condition is Main Boulder Road over Boulder 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 September 2024.

How much traffic does Main Boulder Road over Boulder River carry?

About 157 vehicles per day (2023 count), of which roughly 17% are trucks.

How long is Main Boulder Road over Boulder River?

The structure is 35 ft (10.7 m) long with a longest span of 32 ft (9.8 m) and a deck 15 ft wide.

Who owns Main Boulder Road over Boulder River?

It is owned by the County Highway Agency.