US Bridges

Milligan Road over Porter Canal

Fair

Bonneville County, Idaho · In Idaho Falls · Structure no. 000000000031408

Built
2005
20 years old
Condition
Fair
inspected March 2021
Type
Frame
Concrete
Length
26 ft
1 main span
Daily traffic
400
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

Milligan Road over Porter Canal is a concrete frame carrying Milligan Road over Porter Canal in Bonneville County, Idaho. It was built in 2005, so it is 20 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.

It carries about 400 vehicles a day, roughly 10% of them trucks, projected to reach 600 by 2039. The structure is 26 ft (7.9 m) long and 60 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesMilligan Road
CrossesPorter Canal
LocationIn Idaho Falls
RouteCity Street 0
CountyBonneville County
StateIdaho
Coordinates43.48858, -112.04881
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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMarch 2021
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry9: Superior to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating92 US tons
Inventory rating55 US tons

Structure

Structure typeFrame
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 25 or greater
Structure length26 ft (7.9 m)
Longest span26 ft (7.9 m)
Deck width60 ft (18.3 m)
Roadway width47 ft (14.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic400 (2023)
Projected traffic600 by 2039
Trucks10%
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

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Milligan Road over Porter Canal built?

It was built in 2005, making it 20 years old in 2025.

What condition is Milligan Road over Porter Canal 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 March 2021.

How much traffic does Milligan Road over Porter Canal carry?

About 400 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is Milligan Road over Porter Canal?

The structure is 26 ft (7.9 m) long with a longest span of 26 ft (7.9 m) and a deck 60 ft wide.

Who owns Milligan Road over Porter Canal?

It is owned by the City or Municipal Highway Agency.