US Bridges

Fdr #8983 over N Fk Sun River

Poor

Lewis and Clark County, Montana · Hannan Gulch · Structure no. 011501000000015

Built
1927
98 years old
Condition
Poor
inspected May 2023
Type
Truss - Thru
Steel
Length
273 ft
2 main spans
Daily traffic
99
Owner
Federal
U.S. Forest Service

About this bridge

Fdr #8983 over N Fk Sun River is a steel truss - thru carrying Fdr #8983 over N Fk Sun River in Lewis and Clark County, Montana. It was built in 1927, so it is 98 years old, older than the Montana average of 47 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.

It carries about 99 vehicles a day, projected to reach 148 by 2045. The structure is 273 ft (83.2 m) long and 12 ft wide. If it were closed, the detour would be 98.2 mi (158 km).

Location

Open in Google Maps
CarriesFdr #8983
CrossesN Fk Sun River
LocationHannan Gulch
RouteFederal Lands Road 8983
CountyLewis and Clark County
StateMontana
Coordinates47.6162, -112.73442
Functional classRural Local

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
Deck7 GoodSome minor problems.
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 protection7 GoodSome minor problems.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment4: Meets minimum tolerable limits to be left in place as is
Operating rating23.6 US tons
Inventory rating17.5 US tons

Structure

Structure typeTruss - Thru
MaterialSteel
DeckWood or timber
Main spans2 (+4 approach)
Design loadH 10
Structure length273 ft (83.2 m)
Longest span106 ft (32.3 m)
Deck width12 ft (3.7 m)
Roadway width11 ft (3.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic99 (—)
Projected traffic148 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 Fdr #8983 over N Fk Sun River built?

It was built in 1927, making it 98 years old in 2025.

What condition is Fdr #8983 over N Fk Sun River 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 May 2023.

How much traffic does Fdr #8983 over N Fk Sun River carry?

About 99 vehicles per day (latest count).

How long is Fdr #8983 over N Fk Sun River?

The structure is 273 ft (83.2 m) long with a longest span of 106 ft (32.3 m) and a deck 12 ft wide.

Who owns Fdr #8983 over N Fk Sun River?

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