US Bridges

County Road 129B over Mid Fk. Little Snake Rvr

Fair

Routt County, Colorado · 0.3 MI NE of CO RD 129 · Structure no. 107129B00.30939

Built
1985
40 years old
Condition
Fair
inspected October 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
85 ft
3 main spans
Daily traffic
23
2023 count
Owner
County
County Highway Agency

About this bridge

County Road 129B over Mid Fk. Little Snake Rvr is a steel stringer/multi-beam or girder carrying County Road 129B over Mid Fk. Little Snake Rvr in Routt County, Colorado. It was built in 1985, so it is 40 years old, younger than the Colorado average of 42.2 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 23 vehicles a day, roughly 50% of them trucks, projected to reach 28 by 2042. The structure is 85 ft (26 m) long and 14 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesCounty Road 129B
CrossesMid Fk. Little Snake Rvr
Location0.3 MI NE of CO RD 129
RouteCounty Highway 0
CountyRoutt County
StateColorado
Coordinates40.99051, -107.04442
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating31.3 US tons
Inventory rating23.4 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckWood or timber
Main spans3
Design loadHS 20
Structure length85 ft (26 m)
Longest span30 ft (9.1 m)
Deck width14 ft (4.3 m)
Roadway width14 ft (4.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic23 (2023)
Projected traffic28 by 2042
Trucks50%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.8 mi (159 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedWidening of existing bridge without deck rehabilitation
Estimated improvement cost$464,000 (2018 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was County Road 129B over Mid Fk. Little Snake Rvr built?

It was built in 1985, making it 40 years old in 2025.

What condition is County Road 129B over Mid Fk. Little Snake Rvr 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 October 2024.

How much traffic does County Road 129B over Mid Fk. Little Snake Rvr carry?

About 23 vehicles per day (2023 count), of which roughly 50% are trucks.

How long is County Road 129B over Mid Fk. Little Snake Rvr?

The structure is 85 ft (26 m) long with a longest span of 30 ft (9.1 m) and a deck 14 ft wide.

Who owns County Road 129B over Mid Fk. Little Snake Rvr?

It is owned by the County Highway Agency.