US Bridges

SH 21 over Mores Cr.;at Minniha CR

Fair

Boise County, Idaho · 8.9 S. Idaho City · Structure no. 000000000012840

Built
1990
35 years old
Condition
Fair
inspected October 2023
Type
Slab
Concrete Continuous
Length
81 ft
2 main spans
Daily traffic
2,000
2023 count
Owner
State
State Highway Agency

About this bridge

SH 21 over Mores Cr.;at Minniha CR is a concrete continuous slab carrying SH 21 over Mores Cr.;at Minniha CR in Boise County, Idaho. It was built in 1990, so it is 35 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 2,000 vehicles a day, roughly 18% of them trucks, projected to reach 3,000 by 2042. The structure is 81 ft (24.8 m) long and 40 ft wide. If it were closed, the detour would be 29.8 mi (48 km).

Location

Open in Google Maps
CarriesSH 21
CrossesMores Cr.;at Minniha CR
Location8.9 S. Idaho City
RouteState Highway 21
CountyBoise County
StateIdaho
Coordinates43.73031, -115.93919
Functional classRural Minor Arterial

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 inspectionOctober 2023
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating99.9 US tons
Inventory rating72 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHS 25 or greater
Structure length81 ft (24.8 m)
Longest span40 ft (12.1 m)
Deck width40 ft (12.1 m)
Roadway width37 ft (11.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,000 (2023)
Projected traffic3,000 by 2042
Trucks18%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed29.8 mi (48 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState 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 SH 21 over Mores Cr.;at Minniha CR built?

It was built in 1990, making it 35 years old in 2025.

What condition is SH 21 over Mores Cr.;at Minniha CR 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 2023.

How much traffic does SH 21 over Mores Cr.;at Minniha CR carry?

About 2,000 vehicles per day (2023 count), of which roughly 18% are trucks.

How long is SH 21 over Mores Cr.;at Minniha CR?

The structure is 81 ft (24.8 m) long with a longest span of 40 ft (12.1 m) and a deck 40 ft wide.

Who owns SH 21 over Mores Cr.;at Minniha CR?

It is owned by the State Highway Agency.