US Bridges

Wahlquist Br Road over Rock Creek

Poor

Missoula County, Montana · Ambrose Rock CR · Structure no. 011603000000085

Built
1961
64 years old
Condition
Poor
inspected July 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
120 ft
3 main spans
Daily traffic
50
Owner
Federal
U.S. Forest Service

About this bridge

Wahlquist Br Road over Rock Creek is a wood or timber stringer/multi-beam or girder carrying Wahlquist Br Road over Rock Creek in Missoula County, Montana. It was built in 1961, so it is 64 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 50 vehicles a day, projected to reach 75 by 2045. The structure is 120 ft (36.5 m) long and 15 ft wide. If it were closed, the detour would be 98.2 mi (158 km).

Location

Open in Google Maps
CarriesWahlquist Br Road
CrossesRock Creek
LocationAmbrose Rock CR
RouteFederal Lands Road 428
CountyMissoula County
StateMontana
Coordinates46.50749, -113.77432
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Substructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; action required to protect exposed foundations
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating33.6 US tons
Inventory rating25.7 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans3
Design loadHS 25 or greater
Structure length120 ft (36.5 m)
Longest span40 ft (12.1 m)
Deck width15 ft (4.7 m)
Roadway width14 ft (4.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic50 (—)
Projected traffic75 by 2045
Trucks—
Lanes on structure1
Traffic directionOne-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 Wahlquist Br Road over Rock Creek built?

It was built in 1961, making it 64 years old in 2025.

What condition is Wahlquist Br Road over Rock Creek 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 July 2023.

How much traffic does Wahlquist Br Road over Rock Creek carry?

About 50 vehicles per day (latest count).

How long is Wahlquist Br Road over Rock Creek?

The structure is 120 ft (36.5 m) long with a longest span of 40 ft (12.1 m) and a deck 15 ft wide.

Who owns Wahlquist Br Road over Rock Creek?

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