US Bridges

Idlewild Lane over Big Thompson River

Fair

Larimer County, Colorado · 15 Ft S of US HWY 34 · Structure no. LRB6-1372BTC-A

Built
2019
6 years old
Condition
Fair
inspected May 2023
Type
Box Beam or Girders - Multiple
Prestressed Concrete
Length
67 ft
1 main span
Daily traffic
90
2023 count
Owner
County
County Highway Agency

About this bridge

Idlewild Lane over Big Thompson River is a prestressed concrete box beam or girders - multiple carrying Idlewild Lane over Big Thompson River in Larimer County, Colorado. It was built in 2019, so it is 6 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 6 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 90 vehicles a day, roughly 14% of them trucks, projected to reach 112 by 2042. The structure is 67 ft (20.5 m) long and 23 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesIdlewild Lane
CrossesBig Thompson River
Location15 Ft S of US HWY 34
RouteCounty Highway 0
CountyLarimer County
StateColorado
Coordinates40.42668, -105.30178
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.
Substructure8 Very GoodNo problems noted.
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 evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment5: Somewhat better than minimum adequacy to tolerate being left in place as is
Operating rating47.2 US tons
Inventory rating36.4 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHL 93
Structure length67 ft (20.5 m)
Longest span60 ft (18.4 m)
Deck width23 ft (6.9 m)
Roadway width20 ft (6.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic90 (2023)
Projected traffic112 by 2042
Trucks14%
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

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was Idlewild Lane over Big Thompson River built?

It was built in 2019, making it 6 years old in 2025.

What condition is Idlewild Lane over Big Thompson River 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 May 2023.

How much traffic does Idlewild Lane over Big Thompson River carry?

About 90 vehicles per day (2023 count), of which roughly 14% are trucks.

How long is Idlewild Lane over Big Thompson River?

The structure is 67 ft (20.5 m) long with a longest span of 60 ft (18.4 m) and a deck 23 ft wide.

Who owns Idlewild Lane over Big Thompson River?

It is owned by the County Highway Agency.