US Bridges

Thunder Mt RD over Trapper Creek

Good

Valley County, Idaho · 4.5 MI SW Riordan Lake · Structure no. 040204000012672

Built
2009
16 years old
Condition
Good
inspected September 2023
Type
Other
Wood or Timber
Length
28 ft
1 main span
Daily traffic
50
Owner
Federal
U.S. Forest Service

About this bridge

Thunder Mt RD over Trapper Creek is a wood or timber other carrying Thunder Mt RD over Trapper Creek in Valley County, Idaho. It was built in 2009, so it is 16 years old, younger than the Idaho average of 45.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 50 vehicles a day, projected to reach 75 by 2045. The structure is 28 ft (8.5 m) long and 16 ft wide. If it were closed, the detour would be 98.2 mi (158 km).

Location

Open in Google Maps
CarriesThunder Mt RD
CrossesTrapper Creek
Location4.5 MI SW Riordan Lake
RouteFederal Lands Road 440
CountyValley County
StateIdaho
Coordinates44.7955, -115.4839
Functional classRural Local

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation7: Better than present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating62.2 US tons
Inventory rating47.8 US tons

Structure

Structure typeOther
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadHS 20
Structure length28 ft (8.5 m)
Longest span27 ft (8.2 m)
Deck width16 ft (4.9 m)
Roadway width15 ft (4.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic50 (—)
Projected traffic75 by 2045
Trucks—
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.2 mi (158 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerU.S. Forest Service
Maintained byU.S. Forest Service
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Thunder Mt RD over Trapper Creek built?

It was built in 2009, making it 16 years old in 2025.

What condition is Thunder Mt RD over Trapper Creek in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in September 2023.

How much traffic does Thunder Mt RD over Trapper Creek carry?

About 50 vehicles per day (latest count).

How long is Thunder Mt RD over Trapper Creek?

The structure is 28 ft (8.5 m) long with a longest span of 27 ft (8.2 m) and a deck 16 ft wide.

Who owns Thunder Mt RD over Trapper Creek?

It is owned by the U.S. Forest Service.