US Bridges

I-71 Nc over I-75

Fair

Boone County, Kentucky · Sbl over I-75 Interchange · Structure no. 008B00042L

Built
1967
58 years old
Condition
Fair
inspected June 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
307 ft
4 main spans
Daily traffic
20,852
2023 count
Owner
State
State Highway Agency

About this bridge

I-71 Nc over I-75 is a steel stringer/multi-beam or girder carrying I-71 Nc over I-75 in Boone County, Kentucky. It was built in 1967, so it is 58 years old, older than the Kentucky average of 46.6 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 20,852 vehicles a day, roughly 34% of them trucks, projected to reach 25,856 by 2043. The structure is 307 ft (93.6 m) long and 27 ft wide.

Location

Open in Google Maps
CarriesI-71 Nc
CrossesI-75
LocationSbl over I-75 Interchange
RouteInterstate 71
CountyBoone County
StateKentucky
Coordinates38.87667, -84.625
Functional classRural Principal Arterial - Interstate

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.
Last inspectionJune 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 geometry2: Basically intolerable, requiring high priority of replacement
Approach roadway alignment7: Better than present minimum criteria
Operating rating64.2 US tons
Inventory rating38.5 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length307 ft (93.6 m)
Longest span82 ft (25 m)
Deck width27 ft (8.2 m)
Roadway width22 ft (6.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic20,852 (2023)
Projected traffic25,856 by 2043
Trucks34%
Lanes on structure1
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed—
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusPossibly eligible for the National Register; requires further investigation
Work proposedWidening with deck rehabilitation or replacement
Estimated improvement cost$1 million
NavigationNo navigation control on waterway

Frequently asked questions

When was I-71 Nc over I-75 built?

It was built in 1967, making it 58 years old in 2025.

What condition is I-71 Nc over I-75 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 June 2023.

How much traffic does I-71 Nc over I-75 carry?

About 20,852 vehicles per day (2023 count), of which roughly 34% are trucks.

How long is I-71 Nc over I-75?

The structure is 307 ft (93.6 m) long with a longest span of 82 ft (25 m) and a deck 27 ft wide.

Who owns I-71 Nc over I-75?

It is owned by the State Highway Agency.