US Bridges

I 90 over Greenough Dr-Rattlesnake

Fair

Missoula County, Montana · Missoula · Structure no. I00090105+04671

Built
1966
59 years old
Condition
Fair
inspected October 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
245 ft
4 main spans
Daily traffic
15,284
2023 count
Owner
State
State Highway Agency

About this bridge

I 90 over Greenough Dr-Rattlesnake is a prestressed concrete stringer/multi-beam or girder carrying I 90 over Greenough Dr-Rattlesnake in Missoula County, Montana. It was built in 1966, so it is 59 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 15,284 vehicles a day, roughly 8% of them trucks, projected to reach 16,277 by 2043. The structure is 245 ft (74.6 m) long and 38 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI 90
CrossesGreenough Dr-Rattlesnake
LocationMissoula
RouteInterstate 90
CountyMissoula County
StateMontana
Coordinates46.87243, -113.9841
Functional classUrban 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.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
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 rating56 US tons
Inventory rating25 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length245 ft (74.6 m)
Longest span101 ft (30.9 m)
Deck width38 ft (11.6 m)
Roadway width37 ft (11.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic15,284 (2023)
Projected traffic16,277 by 2043
Trucks8%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway and waterway
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—
NavigationNo navigation control on waterway

Frequently asked questions

When was I 90 over Greenough Dr-Rattlesnake built?

It was built in 1966, making it 59 years old in 2025.

What condition is I 90 over Greenough Dr-Rattlesnake 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 October 2024.

How much traffic does I 90 over Greenough Dr-Rattlesnake carry?

About 15,284 vehicles per day (2023 count), of which roughly 8% are trucks.

How long is I 90 over Greenough Dr-Rattlesnake?

The structure is 245 ft (74.6 m) long with a longest span of 101 ft (30.9 m) and a deck 38 ft wide.

Who owns I 90 over Greenough Dr-Rattlesnake?

It is owned by the State Highway Agency.