US Bridges

Potlatch Road over Black Prince Trestle

PoorPosted for load

Shoshone County, Idaho · 6.6 E. Calder · Structure no. 000000000030996

Built
1912
113 years old, rebuilt 1991
Condition
Poor
inspected August 2024
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
140 ft
10 main spans
Daily traffic
100
2023 count
Owner
County
County Highway Agency

About this bridge

Potlatch Road over Black Prince Trestle is a wood or timber stringer/multi-beam or girder carrying Potlatch Road over Black Prince Trestle in Shoshone County, Idaho. It was built in 1912 and reconstructed in 1991, so it is 113 years old, older than the Idaho average of 45.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. Its operating status is: posted for load restriction.

It carries about 100 vehicles a day, roughly 5% of them trucks, projected to reach 150 by 2039. The structure is 140 ft (42.7 m) long and 14 ft wide. If it were closed, the detour would be 19.9 mi (32 km).

CarriesPotlatch Road
CrossesBlack Prince Trestle
Location6.6 E. Calder
RouteCounty Highway 0
StateIdaho
Coordinates47.26564, -116.05894
Functional classRural Minor Collector

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionAugust 2024
Inspection intervalevery 12 months
Operating statusPosted for load restriction
ScourUnknown foundation; not evaluated for scour
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating44 US tons
Inventory rating32 US tons

Structure

MaterialWood or Timber
DeckWood or timber
Main spans10
Design loadHS 20
Structure length140 ft (42.7 m)
Longest span14 ft (4.3 m)
Deck width14 ft (4.3 m)
Roadway width13 ft (3.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic100 (2023)
Projected traffic150 by 2039
Trucks5%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed19.9 mi (32 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$1.3 million (2019 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Potlatch Road over Black Prince Trestle built?

It was built in 1912, making it 113 years old in 2025. It was reconstructed in 1991.

What condition is Potlatch Road over Black Prince Trestle in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in August 2024.

How much traffic does Potlatch Road over Black Prince Trestle carry?

About 100 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is Potlatch Road over Black Prince Trestle?

The structure is 140 ft (42.7 m) long with a longest span of 14 ft (4.3 m) and a deck 14 ft wide.

Who owns Potlatch Road over Black Prince Trestle?

It is owned by the County Highway Agency.