US Bridges

County Road 21I over Illinois River

Fair

Jackson County, Colorado · 0.4 MI E of ST HWY 125 · Structure no. 057021I00.40026

Built
1980
45 years old
Condition
Fair
inspected November 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
31 ft
1 main span
Daily traffic
57
2023 count
Owner
County
County Highway Agency

About this bridge

County Road 21I over Illinois River is a steel stringer/multi-beam or girder carrying County Road 21I over Illinois River in Jackson County, Colorado. It was built in 1980, so it is 45 years old, older 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 57 vehicles a day, roughly 35% of them trucks, projected to reach 74 by 2043. The structure is 31 ft (9.6 m) long and 24 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

Open in Google Maps
CarriesCounty Road 21I
CrossesIllinois River
Location0.4 MI E of ST HWY 125
RouteCounty Highway 0
CountyJackson County
StateColorado
Coordinates40.44489, -106.14308
Functional classRural Minor Collector

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionNovember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being 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 rating47.5 US tons
Inventory rating28.4 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans1
Design loadHS 20
Structure length31 ft (9.6 m)
Longest span29 ft (8.8 m)
Deck width24 ft (7.3 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic57 (2023)
Projected traffic74 by 2043
Trucks35%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.2 mi (10 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—
NavigationNo navigation control on waterway

Frequently asked questions

When was County Road 21I over Illinois River built?

It was built in 1980, making it 45 years old in 2025.

What condition is County Road 21I over Illinois 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 November 2024.

How much traffic does County Road 21I over Illinois River carry?

About 57 vehicles per day (2023 count), of which roughly 35% are trucks.

How long is County Road 21I over Illinois River?

The structure is 31 ft (9.6 m) long with a longest span of 29 ft (8.8 m) and a deck 24 ft wide.

Who owns County Road 21I over Illinois River?

It is owned by the County Highway Agency.