US Bridges

I 90 over Ronan Ranch Road

Fair

Stillwater County, Montana · 7.4M W Park City · Structure no. I00090419+00261

Built
1970
55 years old
Condition
Fair
inspected December 2023
Type
Slab
Concrete Continuous
Length
79 ft
3 main spans
Daily traffic
6,161
2023 count
Owner
State
State Highway Agency

About this bridge

I 90 over Ronan Ranch Road is a concrete continuous slab carrying I 90 over Ronan Ranch Road in Stillwater County, Montana. It was built in 1970, so it is 55 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.

It carries about 6,161 vehicles a day, roughly 20% of them trucks, projected to reach 6,715 by 2043. The structure is 79 ft (24.1 m) long and 54 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI 90
CrossesRonan Ranch Road
Location7.4M W Park City
RouteInterstate 90
CountyStillwater County
StateMontana
Coordinates45.60006, -109.06175
Functional classRural Principal Arterial - Interstate

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.
Last inspectionDecember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating32 US tons
Inventory rating24 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length79 ft (24.1 m)
Longest span30 ft (9.1 m)
Deck width54 ft (16.5 m)
Roadway width52 ft (15.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,161 (2023)
Projected traffic6,715 by 2043
Trucks20%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was I 90 over Ronan Ranch Road built?

It was built in 1970, making it 55 years old in 2025.

What condition is I 90 over Ronan Ranch Road 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 December 2023.

How much traffic does I 90 over Ronan Ranch Road carry?

About 6,161 vehicles per day (2023 count), of which roughly 20% are trucks.

How long is I 90 over Ronan Ranch Road?

The structure is 79 ft (24.1 m) long with a longest span of 30 ft (9.1 m) and a deck 54 ft wide.

Who owns I 90 over Ronan Ranch Road?

It is owned by the State Highway Agency.