US Bridges

County Road 321 over I 70 Ml

Fair

Clear Creek County, Colorado · 8 MI E of Eisenhower Tunn · Structure no. F-13-T

Built
1971
54 years old
Condition
Fair
inspected April 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
204 ft
2 main spans
Daily traffic
59
2024 count
Owner
State
State Highway Agency

About this bridge

County Road 321 over I 70 Ml is a steel continuous stringer/multi-beam or girder carrying County Road 321 over I 70 Ml in Clear Creek County, Colorado. It was built in 1971, so it is 54 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 59 vehicles a day, roughly 8% of them trucks, projected to reach 74 by 2044. The structure is 204 ft (62.2 m) long and 36 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesCounty Road 321
CrossesI 70 Ml
Location8 MI E of Eisenhower Tunn
RouteCounty Highway 0
CountyClear Creek County
StateColorado
Coordinates39.69229, -105.8052
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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry9: Superior to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating30.3 US tons
Inventory rating23.6 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length204 ft (62.2 m)
Longest span104 ft (31.7 m)
Deck width36 ft (11.1 m)
Roadway width34 ft (10.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic59 (2024)
Projected traffic74 by 2044
Trucks8%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
Detour if closed3.1 mi (5 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState 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 321 over I 70 Ml built?

It was built in 1971, making it 54 years old in 2025.

What condition is County Road 321 over I 70 Ml 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 April 2023.

How much traffic does County Road 321 over I 70 Ml carry?

About 59 vehicles per day (2024 count), of which roughly 8% are trucks.

How long is County Road 321 over I 70 Ml?

The structure is 204 ft (62.2 m) long with a longest span of 104 ft (31.7 m) and a deck 36 ft wide.

Who owns County Road 321 over I 70 Ml?

It is owned by the State Highway Agency.