US Bridges

Grimes Creek Road over Grimes Creek

Fair

Boise County, Idaho · 0.9 N. 4.7 W. Idaho City · Structure no. 000000000026695

Built
1960
65 years old
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
82 ft
2 main spans
Daily traffic
20
2023 count
Owner
County
County Highway Agency

About this bridge

Grimes Creek Road over Grimes Creek is a steel continuous stringer/multi-beam or girder carrying Grimes Creek Road over Grimes Creek in Boise County, Idaho. It was built in 1960, so it is 65 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 20 vehicles a day, projected to reach 30 by 2042. The structure is 82 ft (25 m) long and 15 ft wide. If it were closed, the detour would be 18 mi (29 km).

Location

Open in Google Maps
CarriesGrimes Creek Road
CrossesGrimes Creek
Location0.9 N. 4.7 W. Idaho City
RouteCounty Highway 0
CountyBoise County
StateIdaho
Coordinates43.84221, -115.92412
Functional classRural Minor Collector

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.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourUnknown foundation; not evaluated for scour
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 adequacy9: Superior to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating45 US tons
Inventory rating27 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckWood or timber
Main spans2
Design loadH 20
Structure length82 ft (25 m)
Longest span45 ft (13.7 m)
Deck width15 ft (4.6 m)
Roadway width13 ft (3.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic20 (2023)
Projected traffic30 by 2042
Trucks0%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed18 mi (29 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$803,000 (2019 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Grimes Creek Road over Grimes Creek built?

It was built in 1960, making it 65 years old in 2025.

What condition is Grimes Creek Road over Grimes Creek 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 September 2023.

How much traffic does Grimes Creek Road over Grimes Creek carry?

About 20 vehicles per day (2023 count).

How long is Grimes Creek Road over Grimes Creek?

The structure is 82 ft (25 m) long with a longest span of 45 ft (13.7 m) and a deck 15 ft wide.

Who owns Grimes Creek Road over Grimes Creek?

It is owned by the County Highway Agency.