US Bridges

Manhattan S RD over Irrigation Canal 117

Fair

Gallatin County, Montana · 1M S Manhattan · Structure no. L16441000+02001

Built
1956
69 years old
Condition
Fair
inspected November 2023
Type
Slab
Concrete
Length
31 ft
1 main span
Daily traffic
100
2025 count
Owner
County
County Highway Agency

About this bridge

Manhattan S RD over Irrigation Canal 117 is a concrete slab carrying Manhattan S RD over Irrigation Canal 117 in Gallatin County, Montana. It was built in 1956, so it is 69 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 31 ft (9.6 m) long and 27 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesManhattan S RD
CrossesIrrigation Canal 117
Location1M S Manhattan
RouteCounty Highway 16441
CountyGallatin County
StateMontana
Coordinates45.84556, -111.32657
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionNovember 2023
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 geometry6: Equal to present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating35.3 US tons
Inventory rating20.9 US tons

Structure

Structure typeSlab
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadUnknown
Structure length31 ft (9.6 m)
Longest span31 ft (9.6 m)
Deck width27 ft (8.1 m)
Roadway width24 ft (7.3 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 closed1.2 mi (2 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 Manhattan S RD over Irrigation Canal 117 built?

It was built in 1956, making it 69 years old in 2025.

What condition is Manhattan S RD over Irrigation Canal 117 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 November 2023.

How much traffic does Manhattan S RD over Irrigation Canal 117 carry?

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

How long is Manhattan S RD over Irrigation Canal 117?

The structure is 31 ft (9.6 m) long with a longest span of 31 ft (9.6 m) and a deck 27 ft wide.

Who owns Manhattan S RD over Irrigation Canal 117?

It is owned by the County Highway Agency.