US Bridges

Hells Gate RD over Tammany Creek

FairPosted for load

Nez Perce County, Idaho · In Hells Gate State Park · Structure no. 000000000029975

Built
1959
66 years old
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
42 ft
1 main span
Daily traffic
330
2023 count
Owner
State
State Park, Forest, or Reservation Agency

About this bridge

Hells Gate RD over Tammany Creek is a steel stringer/multi-beam or girder carrying Hells Gate RD over Tammany Creek in Nez Perce County, Idaho. It was built in 1959, so it is 66 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 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. Its operating status is: posted for load restriction.

It carries about 330 vehicles a day, roughly 10% of them trucks, projected to reach 495 by 2039. The structure is 42 ft (12.8 m) long and 24 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesHells Gate RD
CrossesTammany Creek
LocationIn Hells Gate State Park
RouteState Lands Road 0
CountyNez Perce County
StateIdaho
Coordinates46.36433, -117.05886
Functional classRural Local

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionSeptember 2023
Inspection intervalevery 24 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 adequacy8: Equal to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating28 US tons
Inventory rating16 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadH 15
Structure length42 ft (12.8 m)
Longest span31 ft (9.4 m)
Deck width24 ft (7.4 m)
Roadway width24 ft (7.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic330 (2023)
Projected traffic495 by 2039
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.8 mi (159 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Park, Forest, or Reservation Agency
Maintained byState Park, Forest, or Reservation Agency
Historic statusHistorical significance not determinable at this time
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$401,000 (2019 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Hells Gate RD over Tammany Creek built?

It was built in 1959, making it 66 years old in 2025.

What condition is Hells Gate RD over Tammany 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 Hells Gate RD over Tammany Creek carry?

About 330 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is Hells Gate RD over Tammany Creek?

The structure is 42 ft (12.8 m) long with a longest span of 31 ft (9.4 m) and a deck 24 ft wide.

Who owns Hells Gate RD over Tammany Creek?

It is owned by the State Park, Forest, or Reservation Agency.