US Bridges

S. Dewey Ave over Mill Slough

FairPosted for load

Canyon County, Idaho · At Middleton Scl · Structure no. 000000000027310

Built
1980
45 years old
Condition
Fair
inspected November 2024
Type
Tee Beam
Prestressed Concrete
Length
28 ft
1 main span
Daily traffic
440
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

S. Dewey Ave over Mill Slough is a prestressed concrete tee beam carrying S. Dewey Ave over Mill Slough in Canyon County, Idaho. It was built in 1980, so it is 45 years old, younger than the Idaho average of 45.3 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. Its operating status is: posted for load restriction.

It carries about 440 vehicles a day, roughly 5% of them trucks, projected to reach 660 by 2039. The structure is 28 ft (8.5 m) long and 40 ft wide. If it were closed, the detour would be 0.6 mi (1 km).

Location

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CarriesS. Dewey Ave
CrossesMill Slough
LocationAt Middleton Scl
RouteCounty Highway 0
CountyCanyon County
StateIdaho
Coordinates43.70481, -116.61966
Functional classUrban 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.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionNovember 2024
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating27 US tons
Inventory rating13 US tons

Structure

Structure typeTee Beam
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadH 15
Structure length28 ft (8.5 m)
Longest span27 ft (8.2 m)
Deck width40 ft (12.2 m)
Roadway width31 ft (9.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic440 (2023)
Projected traffic660 by 2039
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed0.6 mi (1 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$582,000 (2020 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was S. Dewey Ave over Mill Slough built?

It was built in 1980, making it 45 years old in 2025.

What condition is S. Dewey Ave over Mill Slough 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 2024.

How much traffic does S. Dewey Ave over Mill Slough carry?

About 440 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is S. Dewey Ave over Mill Slough?

The structure is 28 ft (8.5 m) long with a longest span of 27 ft (8.2 m) and a deck 40 ft wide.

Who owns S. Dewey Ave over Mill Slough?

It is owned by the City or Municipal Highway Agency.