US Bridges

SH 21 over Mores Cr;lucky Peak Res.

Fair

Ada County, Idaho · 17 N. Boise · Structure no. 000000000012815

Built
1953
72 years old
Condition
Fair
inspected October 2024
Type
Truss - Deck
Steel Continuous
Length
848 ft
2 main spans
Daily traffic
3,500
2023 count
Owner
State
State Highway Agency

About this bridge

SH 21 over Mores Cr;lucky Peak Res. is a steel continuous truss - deck carrying SH 21 over Mores Cr;lucky Peak Res. in Ada County, Idaho. It was built in 1953, so it is 72 years old, older 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 5 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 3,500 vehicles a day, roughly 7% of them trucks, projected to reach 5,250 by 2042. The structure is 848 ft (258.5 m) long and 32 ft wide. If it were closed, the detour would be 75.2 mi (121 km).

Location

Open in Google Maps
CarriesSH 21
CrossesMores Cr;lucky Peak Res.
Location17 N. Boise
RouteState Highway 21
CountyAda County
StateIdaho
Coordinates43.59142, -115.99878
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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
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 geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating39 US tons
Inventory rating24 US tons

Structure

Structure typeTruss - Deck
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans2 (+4 approach)
Design loadHS 15
Structure length848 ft (258.5 m)
Longest span432 ft (131.6 m)
Deck width32 ft (9.7 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,500 (2023)
Projected traffic5,250 by 2042
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed75.2 mi (121 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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$10.7 million (2020 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SH 21 over Mores Cr;lucky Peak Res. built?

It was built in 1953, making it 72 years old in 2025.

What condition is SH 21 over Mores Cr;lucky Peak Res. 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 SH 21 over Mores Cr;lucky Peak Res. carry?

About 3,500 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is SH 21 over Mores Cr;lucky Peak Res.?

The structure is 848 ft (258.5 m) long with a longest span of 432 ft (131.6 m) and a deck 32 ft wide.

Who owns SH 21 over Mores Cr;lucky Peak Res.?

It is owned by the State Highway Agency.